Comerica (CMA) 10-Q 29 Apr 20 2020 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2020	Apr. 24, 2020
Document And Entity Information [Abstract]
Document Quarterly Report	true
Title of 12(b) Security	Common Stock, $5 par value
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	38-1998421
Document Type	10-Q
Document Period End Date	Mar. 31, 2020
Amendment Flag	false
Entity Registrant Name	Comerica Incorporated
Entity Central Index Key	0000028412
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		139,034,717
Entity File Number	1-10706
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Address, Address Line One	1717 Main Street, MC 6404
Entity Address, City or Town	Dallas
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	75201
City Area Code	(214)
Local Phone Number	462-6831
Document Transition Report	false
Trading Symbol	CMA
Security Exchange Name	NYSE

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
ASSETS
Cash and due from banks	$ 848	$ 973
Interest-bearing deposits with banks	4,007	4,845
Other short-term investments	138	155
Investment securities available-for-sale	13,041	12,398
Commercial loans	34,249	31,473
Real estate construction loans	3,756	3,455
Commercial mortgage loans	9,698	9,559
Lease financing	584	588
International loans	1,035	1,009
Residential mortgage loans	1,821	1,845
Consumer loans	2,315	2,440
Total loans	53,458	50,369
Less allowance for loan losses	(916)	(637)
Net loans	52,542	49,732
Premises and equipment	454	457
Accrued income and other assets	5,307	4,842
Total assets	76,337	73,402
LIABILITIES AND SHAREHOLDERS' EQUITY
Noninterest-bearing deposits	27,646	27,382
Money market and interest-bearing checking deposits	24,475	24,527
Savings deposits	2,258	2,184
Customer certificates of deposit	2,958	2,978
Other time deposits	0	133
Foreign office time deposits	29	91
Total interest-bearing deposits	29,720	29,913
Total deposits	57,366	57,295
Short-term borrowings	2,263	71
Accrued expenses and other liabilities	1,872	1,440
Medium- and long-term debt	7,434	7,269
Total liabilities	68,935	66,075
Common stock - $5 par value: Authorized - 325,000,000 shares; Issued - 228,164,824 shares	1,141	1,141
Capital surplus	2,168	2,174
Accumulated other comprehensive income (loss)	174	(235)
Retained earnings	9,389	9,538
Less cost of common stock in treasury - 89,127,359 shares at 3/31/20 and 86,069,234 shares at 12/31/19	(5,470)	(5,291)
Total shareholders' equity	7,402	7,327
Total liabilities and shareholders' equity	$ 76,337	$ 73,402

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Common stock, par value	$ 5	$ 5
Common stock, authorized shares	325,000,000	325,000,000
Common stock, issued shares	228,164,824	228,164,824
Shares in treasury	89,127,359	86,069,234

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
INTEREST INCOME
Interest and fees on loans		$ 517	$ 621
Interest on investment securities		74	72
Interest on short-term investments		18	17
Total interest income		609	710
INTEREST EXPENSE
Interest on deposits		56	52
Interest on short-term borrowings		0	1
Interest on medium- and long-term debt	[1]	40	51
Total interest expense		96	104
Net interest income		513	606
Provision for credit losses		411	(13)
Net interest income after provision for credit losses		102	619
NONINTEREST INCOME
Card Fees		59	63
Fiduciary income		54	49
Service charges on deposit accounts		49	51
Commercial lending fees		17	22
Foreign exchange income		11	11
Bank-owned life insurance		12	9
Letter of credit fees		9	9
Brokerage fees		7	7
Net securities losses		(1)	(8)
Other noninterest income		20	25
Total noninterest income		237	238
NONINTEREST EXPENSES
Salaries and benefits expense		242	265
Outside processing fee expense		57	63
Occupancy expense		37	37
Software expense		37	29
Equipment expense		12	12
Advertising expense		7	5
FDIC insurance expense		8	5
Other noninterest expenses		25	17
Total noninterest expenses		425	433
(Loss) income before income taxes		(86)	424
(Benefit) provision for income taxes		(21)	85
Net (loss) income		(65)	339
Less income allocated to participating securities		0	2
Net (loss) income attributable to common shares		$ (65)	$ 337
Basic (losses) earnings per common share		$ (0.46)	$ 2.14
Diluted (losses) earnings per common share		$ (0.46)	$ 2.11
Comprehensive income		$ 344	$ 435
Cash dividends declared on common stock		$ 94	$ 105
Cash dividends declared per common share		$ 0.68	$ 0.67
[1]	Includes the effects of hedging.

Consolidated Statements Of Chan

Consolidated Statements Of Changes In Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Capital Surplus	Accumulated Other Comprehensive Loss	Retained Earnings	Treasury Stock
Cumulative effect of change in accounting principle				$ 0
BALANCE (in shares) at Dec. 31, 2018		160.1
BALANCE at Dec. 31, 2018	$ 7,507	$ 1,141	$ 2,148	(609)	$ 8,781	$ (3,954)
Net (loss) income	339				339
Other comprehensive income (loss), net of tax	96			96
Cash dividends declared on common stock	(105)				(105)
Purchase of common stock	(434)		0			(434)
Purchase of common stock (in shares)		(5.2)
Net issuance of common stock under employee stock plans	(4)		(13)		(22)	31
Net issuance of common stock under employee stock plans (in shares)		0.5
Share-based compensation	24		24
BALANCE at Mar. 31, 2019	7,409	$ 1,141	2,159	(513)	8,979	(4,357)
BALANCE (in shares) at Mar. 31, 2019		155.4
BALANCE (in shares) at Dec. 31, 2019		142.1
BALANCE at Dec. 31, 2019	7,327	$ 1,141	2,174	(235)	9,538	(5,291)
Net (loss) income	(65)				(65)
Other comprehensive income (loss), net of tax	409			409
Cash dividends declared on common stock	(94)				(94)
Purchase of common stock	(195)		0			(195)
Purchase of common stock (in shares)		(3.4)
Net issuance of common stock under employee stock plans	(1)		(14)		(3)	16
Net issuance of common stock under employee stock plans (in shares)		0.3
Share-based compensation	8		8
BALANCE at Mar. 31, 2020	$ 7,402	$ 1,141	$ 2,168	$ 174	$ 9,389	$ (5,470)
BALANCE (in shares) at Mar. 31, 2020		139

Consolidated Statements Of Ch_2

Consolidated Statements Of Changes In Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Stockholders' Equity [Abstract]
Cash dividends declared on stock, per common share	$ 0.68	$ 0.67

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
OPERATING ACTIVITIES
Net (loss) income	$ (65)	$ 339
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Provision for credit losses	411	(13)
Benefit for deferred income taxes	(73)	(4)
Depreciation and amortization	26	29
Net periodic defined benefit credit	(5)	(7)
Share-based compensation expense	8	24
Net amortization of securities	1	0
Net securities losses	1	8
Net change in accrued income receivable	8	(20)
Net change in accrued expenses payable	(12)	(27)
Other, net	399	(289)
Net cash provided by operating activities	699	40
INVESTING ACTIVITIES
Maturities and redemptions of investment securities available-for-sale	598	487
Sales of investment securities available-for-sale	0	987
Purchases of investment securities available-for-sale	(920)	(1,532)
Net change in loans	(3,174)	(151)
Net increase in premises and equipment	(15)	(16)
Purchases of Federal Home Loan Bank stock	(31)	(16)
Proceeds from bank-owned life insurance settlements	8	2
Net cash used in investing activities	(3,534)	(239)
FINANCING ACTIVITIES
Net change in deposits	(29)	(1,586)
Net change in short-term borrowings	2,192	891
Issuances and advances of medium- and long-term debt	0	350
Repurchases of common stock	(199)	(443)
Cash dividends paid on common stock	(95)	(99)
Issuances of common stock under employee stock plans	3	6
Net cash provided by (used in) financing activities	1,872	(881)
Net decrease in cash and cash equivalents	(963)	(1,080)
Cash and cash equivalents at beginning of period	5,818	4,561
Cash and cash equivalents at end of period	4,855	3,481
Interest paid	102	98
Income tax paid	$ 3	$ 12

Basis of Presentation and Accou

Basis of Presentation and Accounting Policies	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation and Accounting Policies	BASIS OF PRESENTATION AND ACCOUNTING POLICIES Organization The accompanying unaudited consolidated financial statements were prepared in accordance with United States (U.S.) generally accepted accounting principles (GAAP) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, the statements do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation were included. The results of operations for the three months ended March 31, 2020 are not necessarily indicative of the results that may be expected for the year ending December 31, 2020 . Certain items in prior periods were reclassified to conform to the current presentation. For further information, refer to the consolidated financial statements and footnotes thereto included in the Annual Report of Comerica Incorporated and Subsidiaries (the Corporation) on Form 10-K for the year ended December 31, 2019 . Allowance for Credit Losses The allowance for credit losses includes both the allowance for loan losses and the allowance for credit losses on lending-related commitments. The Corporation disaggregates the loan portfolio into segments for purposes of determining the allowance for credit losses. These segments are based on the level at which the Corporation develops, documents and applies a systematic methodology to determine the allowance for credit losses. The Corporation's portfolio segments are business loans and retail loans. Business loans include the commercial, real estate construction, commercial mortgage, lease financing and international loan portfolios. Retail loans consist of residential mortgage and consumer loans, including home equity loans. Effective January 1, 2020, the Corporation adopted the provisions of Accounting Standards Update (ASU) No. 2016-13, "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments," commonly referred to as the current expected credit loss (CECL) model, for all financial assets, except those accounted for at fair value through net income, using the modified retrospective approach. Under Topic 326, current expected credit losses are estimated over the contractual life of the loan portfolio, considering all available relevant information, including historical and current conditions as well as reasonable and supportable forecasts of future events. The previous accounting principle estimated probable, estimable losses inherent in the portfolio. At adoption, the Corporation’s estimate of current expected credit losses in accordance with Topic 326 resulted in a $17 million day-one decrease in the overall allowance for credit losses, from $668 million at December 31, 2019 under the incurred loss model. The Corporation recognized a corresponding $13 million increase to retained earnings and a $4 million reduction to deferred tax assets. A similar adjustment at December 31, 2019 would have caused a 2-basis-point increase in the Common Equity Tier 1 (CET1) capital ratio. Business loans, comprising approximately 91 percent of the Corporation’s total loan portfolio at transition, consist of loans and lending arrangements with generally short contractual maturities. As a result, the allowance for credit losses for business loans decreased $42 million . The allowance for credit losses increased $25 million for retail loans, given their longer contractual maturities. Topic 326 also requires expected credit losses on available-for-sale (AFS) debt securities to be recorded as an allowance for credit losses. For certain types of debt securities, such as U.S. Treasuries and other securities with government guarantees, entities may expect zero credit losses. The zero-loss expectation applies to all the Corporation’s securities and no allowance for credit losses were recorded on its AFS securities portfolio at transition. Allowance for Loan Losses The allowance for loan losses is estimated on a quarterly basis and represents management’s estimates of current expected credit losses in the Corporation’s loan portfolio. Pools of loans with similar risk characteristics are collectively evaluated while loans that no longer share risk characteristics with loan pools are evaluated individually. Collective loss estimates are determined by applying reserve factors, designed to estimate current expected credit losses, to amortized cost balances over the remaining contractual life of the collectively evaluated portfolio. Loans with similar risk characteristics are aggregated into homogeneous pools. Business loans are assigned to pools based primarily on business line and the Corporation’s internal risk rating system. For retail loans, pools are based on loan type, past due status and credit scores. Reserve factors are based on estimated probability of default for each pool, set to a default horizon based on contractual life, and loss given default. Historical estimates are calibrated to economic forecasts over the reasonable and supportable forecast period based on the projected performance of specific economic variables that statistically correlate with each of the probability of default and loss given default pools. The calculation of current expected credit losses is inherently subjective, as it requires management to exercise judgment in determining appropriate factors used to determine the allowance. Some of the most significant factors in the quantitative allowance estimate are assigning internal risk ratings to loans, selecting the economic forecasts used to calibrate the reserve factors and determining the reasonable and supportable forecast period. • Internal Risk Ratings : Standard loss factors are dependent on loan risk ratings for business loans. Risk ratings are assigned at origination, based on inherent credit risk, and may be updated based on new information that becomes available, periodic reviews of credit quality, a change in borrower performance or modifications to lending agreements. • Economic Forecasts: Management selects economic variables it believes to be most relevant based on the composition of the loan portfolio and customer base, including forecasted levels of employment, gross domestic product, corporate bond and treasury spreads, industrial production levels, consumer and commercial real estate price indices as well as housing statistics. Different economic forecast scenarios ranging from more benign to more severe are evaluated each reporting period to forecast losses over the contractual life of the loan portfolio. • Forecast Period : Economic forecasts are applied over the period management believes it can estimate reasonable and supportable forecasts. Forecast periods may be adjusted in response to changes in the economic environment. To estimate losses for contractual periods that extend beyond the forecast horizon, the Corporation reverts to an average historical loss experience. The Corporation typically forecasts economic variables over a two-year horizon, followed by an immediate reversion to an average historical loss experience that generally incorporates a full economic cycle. Management reviews this methodology on at least an annual basis. The allowance for loan losses also includes qualitative adjustments to bring the allowance to the level management believes is appropriate based on factors that have not otherwise been fully accounted for, including adjustments for foresight risk, input imprecision and model imprecision. Foresight risk reflects the inherent imprecision in forecasting economic variables, including determining the depth and duration of economic cycles and their impact to relevant economic variables. The Corporation may make qualitative adjustments based on its evaluation of different forecast scenarios and known recent events impacting relevant economic variables. Input imprecision factors address the risk that certain model inputs may not reflect all available information including (i) risk factors that have not been fully addressed in internal risk ratings, (ii) changes in lending policies and procedures, (iii) changes in the level and quality of experience held by lending management, (iv) imprecision in the risk rating system and (v) limitations in data available for certain loan portfolios. Model imprecision considers known model limitations and model updates not yet fully reflected in the quantitative estimate. The determination of the appropriate qualitative adjustment is based on management's analysis of current and expected economic conditions and their impact to the portfolio, as well as internal credit risk movements and a qualitative assessment of the lending environment, including underwriting standards. Management recognizes the sensitivity of various assumptions made in the quantitative modeling of expected losses and may adjust reserves depending upon the level of uncertainty that currently exists in one or more assumptions. Credit losses for loans that no longer share risk characteristics with the loan pools are estimated on an individual basis. Individual credit loss estimates are typically performed for nonaccrual loans and modified loans classified as troubled debt restructurings and are based on one of several methods, including the estimated fair value of the underlying collateral, observable market value of similar debt or the present value of expected cash flows. The Corporation considers certain loans to be collateral-dependent if the borrower is experiencing financial difficulty and management expects repayment for the loan to be substantially through the operation or sale of the collateral. For collateral-dependent loans, loss estimates are based on the fair value of collateral, less estimated cost to sell (if applicable). Collateral values supporting individually evaluated loans are assessed quarterly and appraisals are typically obtained at least annually. The total allowance for loan losses is sufficient to absorb expected credit losses over the contractual life of the portfolio. Unanticipated events impacting the economy, including political instability or global events affecting the U.S. economy, could cause changes to expectations for current conditions and economic forecasts that result in an unanticipated increase in the allowance. Significant increases in current portfolio exposures or changes in credit characteristics could also increase the amount of the allowance. Such events, or others of similar nature, may result in the need for additional provision for credit losses in order to maintain an allowance that complies with credit risk and accounting policies. Loans deemed uncollectible are charged off and deducted from the allowance. Recoveries on loans previously charged off are added to the allowance. Credit losses are not estimated for accrued interest receivable as interest that is deemed uncollectible is written off through interest income. Allowance for Credit Losses on Lending-Related Commitments The allowance for credit losses on lending-related commitments estimates current expected credit losses on collective pools of letters of credit and unused commitments to extend credit based on standard reserve factors, determined in a manner similar to business loans, multiplied by a probability of draw estimate, based on historical experience and credit risk, applied to commitment amounts. The allowance for credit losses on lending-related commitments is included in accrued expenses and other liabilities on the Consolidated Balance Sheets, with the corresponding charge included in the provision for credit losses on the Consolidated Statements of Comprehensive Income. Goodwill Effective January 1, 2020, the Corporation prospectively adopted the provisions of ASU No. 2017-04, “Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment,” (ASU 2017-04), eliminating the second step of goodwill impairment testing, under which the implied fair value of goodwill was determined as if the reporting unit were being acquired in a business combination. Under ASU 2017-04, the Corporation will compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for any amount by which the carrying amount exceeds the reporting unit’s fair value, to the extent that the loss recognized does not exceed the amount of goodwill allocated to that reporting unit. The adoption of ASU 2017-04 did not impact the Corporation’s current financial condition or results of operations. Goodwill, included in accrued income and other assets on the Consolidated Balance Sheets, is initially recorded as the excess of the purchase price over the fair value of net assets acquired in a business combination and is subsequently evaluated at least annually for impairment. Goodwill impairment testing is performed at the reporting unit level, equivalent to a business segment or one level below. The Corporation has three reporting units: the Business Bank, the Retail Bank and Wealth Management. The Corporation performs its annual evaluation of goodwill impairment in the third quarter of each year and on an interim basis if events or changes in circumstances between annual tests suggest additional testing may be warranted to determine if goodwill might be impaired. The Corporation may choose to perform a qualitative assessment to determine whether it is more likely than not that the fair value of any reporting unit is less than its carrying amount, including goodwill. Factors considered in the assessment of the likelihood of impairment include macroeconomic conditions, industry and market considerations, stock performance of the Corporation and its peers, financial performance of the reporting units, and previous results of goodwill impairment tests, amongst other factors. Based on the results of the qualitative analysis, the Corporation determines whether a quantitative test is deemed necessary. The quantitative test compares the estimated fair value of identified reporting units with their carrying amount, including goodwill. If the estimated fair value of the reporting unit is less than the carrying value, an impairment charge would be recorded for the excess, not to exceed the amount of goodwill allocated to the reporting unit. Software Effective January 1, 2020, the Corporation adopted the provisions of ASU No. 2018-15, “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract," using a prospective approach for implementation costs incurred subsequent to the adoption of the standard. Amortization expense from capitalized implementation costs of hosting arrangements that are service contracts and fees associated with the hosting elements of the arrangements, are included in software expense in the Consolidated Statements of Comprehensive Income, along with other software-related expenses. For the three months ended March 31, 2020 , software expense included $7 million of hosting fees that would have previously been included in outside processing fee expense. Capitalized software, stated at cost less accumulated amortization, includes purchased software, capitalizable application development costs associated with internally developed software and cloud computing arrangements, including capitalizable implementation costs associated with hosting arrangements that are service contracts. Amortization, computed on the straight-line method, is charged to software expense in the Consolidated Statements of Comprehensive Income over the estimated useful life of the software, generally 5 years, or the term of the hosting arrangement for implementation costs related to service contracts. Cloud computing arrangements include software as a service (SaaS), platform as a service (PaaS), infrastructure as a service (IaaS) and other similar hosting arrangements. The Corporation primarily utilizes SaaS and IaaS arrangements. Capitalized implementation costs of hosting arrangements that are service contracts were insignificant for the three months ended March 31, 2020 . Reference Rate Reform In March 2020, the Financial Accounting Standards Board (FASB) issued ASU No. 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting,” (ASU 2020-04), to provide temporary optional guidance to ease the potential accounting burden of reference rate reform. ASU 2020-04 is effective for eligible contract modifications from January 1, 2020 through December 31, 2022. Approximately 86 percent of the Corporation’s loans at March 31, 2020 were tied to LIBOR. The Corporation uses interest rate swaps to convert variable-LIBOR rate loans to fixed rates for approximately 10 percent of the loan portfolio. Additional contracts with exposure to LIBOR include swaps converted fixed-rate long-term debt to variable LIBOR rates. The Corporation adopted the provisions of ASU 2020-04 for loan contract modifications as of January 1, 2020 and for all existing hedging relationships as of that date or entered into in the first quarter of 2020.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The Corporation utilizes fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures. The determination of fair values of financial instruments often requires the use of estimates. In cases where quoted market values in an active market are not available, the Corporation uses present value techniques and other valuation methods to estimate the fair values of its financial instruments. These valuation methods require considerable judgment and the resulting estimates of fair value can be significantly affected by the assumptions made and methods used. Investment securities available-for-sale, derivatives, deferred compensation plans and equity securities with readily determinable fair values (primarily money market mutual funds) are recorded at fair value on a recurring basis. Additionally, from time to time, the Corporation may be required to record other assets and liabilities at fair value on a nonrecurring basis, such as nonaccrual loans and loans classified as troubled debt restructurings (TDRs), other real estate (primarily foreclosed property), nonmarketable equity securities and certain other assets and liabilities. These nonrecurring fair value adjustments typically involve write-downs of individual assets or application of lower of cost or fair value accounting. Refer to Note 1 to the consolidated financial statements in the Corporation's Annual Report on Form 10-K for the year ended December 31, 2019 for further information about the fair value hierarchy, descriptions of the valuation methodologies and key inputs used to measure financial assets and liabilities recorded at fair value, as well as a description of the methods and significant assumptions used to estimate fair value disclosures for financial instruments not recorded at fair value in their entirety on a recurring basis. Assets and Liabilities Recorded at Fair Value on a Recurring Basis The following tables present the recorded amount of assets and liabilities measured at fair value on a recurring basis as of March 31, 2020 and December 31, 2019 . (in millions) Total Level 1 Level 2 Level 3 March 31, 2020 Deferred compensation plan assets $ 92 $ 92 $ — $ — Equity securities 40 40 — — Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities 2,864 2,864 — — Residential mortgage-backed securities (a) 10,177 — 10,177 — Total investment securities available-for-sale 13,041 2,864 10,177 — Derivative assets: Interest rate contracts 605 — 562 43 Energy derivative contracts 459 — 459 — Foreign exchange contracts 34 — 34 — Total derivative assets 1,098 — 1,055 43 Total assets at fair value $ 14,271 $ 2,996 $ 11,232 $ 43 Derivative liabilities: Interest rate contracts $ 70 $ — $ 70 $ — Energy derivative contracts 454 — 454 — Foreign exchange contracts 27 — 27 — Total derivative liabilities 551 — 551 — Deferred compensation plan liabilities 92 92 — — Total liabilities at fair value $ 643 $ 92 $ 551 $ — December 31, 2019 Deferred compensation plan assets $ 95 $ 95 $ — $ — Equity securities 54 54 — — Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities 2,792 2,792 — — Residential mortgage-backed securities (a) 9,606 — 9,606 — Total investment securities available-for-sale 12,398 2,792 9,606 — Derivative assets: Interest rate contracts 211 — 189 22 Energy derivative contracts 96 — 96 — Foreign exchange contracts 10 — 10 — Total derivative assets 317 — 295 22 Total assets at fair value $ 12,864 $ 2,941 $ 9,901 $ 22 Derivative liabilities: Interest rate contracts $ 39 $ — $ 39 $ — Energy derivative contracts 92 — 92 — Foreign exchange contracts 10 — 10 — Total derivative liabilities 141 — 141 — Deferred compensation plan liabilities 95 95 — — Total liabilities at fair value $ 236 $ 95 $ 141 $ — (a) Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises. There were no transfers of assets or liabilities recorded at fair value on a recurring basis into or out of Level 3 fair value measurements during each of the three-month periods ended March 31, 2020 and 2019 . The following table summarizes the changes in Level 3 assets and liabilities measured at fair value on a recurring basis for the three-month periods ended March 31, 2020 and 2019 . Net Realized/Unrealized Gains (Losses) (Pretax) Recorded in Earnings (a) Balance at Beginning of Period Balance at End of Period Payments, Sales and Redemptions (in millions) Realized Unrealized Three Months Ended March 31, 2020 Derivative assets: Interest rate contracts $ 22 $ — $ 21 $ — $ 43 Three Months Ended March 31, 2019 Derivative assets: Interest rate contracts $ 9 $ — $ 5 $ — $ 14 (a) Realized and unrealized gains and losses due to changes in fair value are recorded in other noninterest income on the Consolidated Statements of Comprehensive Income. Assets and Liabilities at Fair Value on a Nonrecurring Basis The Corporation may be required to record certain assets and liabilities at fair value on a nonrecurring basis. These include assets that are recorded at the lower of cost or fair value, and were recognized at fair value since it was less than cost at the end of the period. The following table presents assets recorded at fair value on a nonrecurring basis at March 31, 2020 and December 31, 2019 . No liabilities were recorded at fair value on a nonrecurring basis at March 31, 2020 and December 31, 2019 . (in millions) Level 3 March 31, 2020 Loans: Commercial $ 89 Lease financing 1 Total assets at fair value $ 90 December 31, 2019 Loans: Commercial $ 70 Total assets at fair value $ 70 Level 3 assets recorded at fair value on a nonrecurring basis at March 31, 2020 and December 31, 2019 included both nonaccrual loans and TDRs for which a specific allowance was established based on the fair value of collateral. The unobservable inputs were the additional adjustments applied by management to the appraised values to reflect such factors as non-current appraisals and revisions to estimated time to sell. These adjustments are determined based on qualitative judgments made by management on a case-by-case basis and are not quantifiable inputs, although they are used in the determination of fair value. Estimated Fair Values of Financial Instruments Not Recorded at Fair Value on a Recurring Basis The Corporation typically holds the majority of its financial instruments until maturity and thus does not expect to realize many of the estimated fair value amounts disclosed. The disclosures also do not include estimated fair value amounts for items that are not defined as financial instruments, but which have significant value. These include such items as core deposit intangibles, the future earnings potential of significant customer relationships and the value of trust operations and other fee generating businesses. The Corporation believes the imprecision of an estimate could be significant. The carrying amount and estimated fair value of financial instruments not recorded at fair value in their entirety on a recurring basis on the Corporation’s Consolidated Balance Sheets are as follows: Carrying Amount Estimated Fair Value (in millions) Total Level 1 Level 2 Level 3 March 31, 2020 Assets Cash and due from banks $ 848 $ 848 $ 848 $ — $ — Interest-bearing deposits with banks 4,007 4,007 4,007 — — Loans held-for-sale 5 5 — 5 — Total loans, net of allowance for loan losses (a) 52,542 52,108 — — 52,108 Customers’ liability on acceptances outstanding 2 2 2 — — Restricted equity investments 279 279 279 — — Nonmarketable equity securities (b) 5 10 Liabilities Demand deposits (noninterest-bearing) 27,646 27,646 — 27,646 — Interest-bearing deposits 26,762 26,762 — 26,762 — Customer certificates of deposit 2,958 2,959 — 2,959 — Total deposits 57,366 57,367 — 57,367 — Short-term borrowings 2,263 2,263 2,263 — — Acceptances outstanding 2 2 2 — — Medium- and long-term debt 7,434 7,224 — 7,224 — Credit-related financial instruments (84 ) (84 ) — — (84 ) December 31, 2019 Assets Cash and due from banks $ 973 $ 973 $ 973 $ — $ — Interest-bearing deposits with banks 4,845 4,845 4,845 — — Loans held-for-sale 6 6 — 6 — Total loans, net of allowance for loan losses (a) 49,732 49,975 — — 49,975 Customers’ liability on acceptances outstanding 2 2 2 — — Restricted equity investments 248 248 248 — — Nonmarketable equity securities (b) 5 10 Liabilities Demand deposits (noninterest-bearing) 27,382 27,382 — 27,382 — Interest-bearing deposits 26,802 26,802 — 26,802 — Certificates of deposit 2,978 2,968 — 2,968 — Other time deposits 133 133 — 133 — Total deposits 57,295 57,285 — 57,285 — Short-term borrowings 71 71 71 — — Acceptances outstanding 2 2 2 — — Medium- and long-term debt 7,269 7,316 — 7,316 — Credit-related financial instruments (57 ) (57 ) — — (57 ) (a) Included $90 million and $70 million of loans recorded at fair value on a nonrecurring basis at March 31, 2020 and December 31, 2019 , respectively. (b) Certain investments that are measured at fair value using the net asset value have not been classified in the fair value hierarchy. The fair value amounts presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets.

Investment Securities

Investment Securities	3 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Investment Securities	INVESTMENT SECURITIES A summary of the Corporation’s investment securities follows: (in millions) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value March 31, 2020 Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities $ 2,746 $ 118 $ — $ 2,864 Residential mortgage-backed securities (a) 9,887 290 — 10,177 Total investment securities available-for-sale $ 12,633 $ 408 $ — $ 13,041 December 31, 2019 Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities $ 2,745 $ 47 $ — $ 2,792 Residential mortgage-backed securities (a) 9,568 66 28 9,606 Total investment securities available-for-sale $ 12,313 $ 113 $ 28 $ 12,398 (a) Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises. A summary of the Corporation’s investment securities in an unrealized loss position as of March 31, 2020 and December 31, 2019 follows: Temporarily Impaired Less than 12 Months 12 Months or more Total (in millions) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses March 31, 2020 Residential mortgage-backed securities (a) $ 110 $ — $ — $ — $ 110 $ — Total temporarily impaired securities $ 110 $ — $ — $ — $ 110 $ — December 31, 2019 Residential mortgage-backed securities (a) $ 1,494 $ 7 $ 1,906 $ 21 $ 3,400 $ 28 Total temporarily impaired securities $ 1,494 $ 7 $ 1,906 $ 21 $ 3,400 $ 28 (a) Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises. Unrealized losses resulted from changes in market interest rates and liquidity. The Corporation’s portfolio is comprised of securities issued or guaranteed by the U.S. government or government-sponsored enterprises. As such, it is expected that the securities would not be settled at a price less than the amortized cost of the investments. Further, the Corporation does not intend to sell the investments and is not more likely than not that it will be required to sell the investments before recovery of amortized costs. Interest receivable on investment securities totaled $20 million at March 31, 2020 and December 31, 2019 , and was included in accrued income and other assets on the Consolidated Balance Sheets. Sales, calls and write-downs of investment securities available-for-sale resulted in the following losses recorded in net securities losses on the Consolidated Statements of Comprehensive Income, computed based on the adjusted cost of the specific security. Three Months Ended March 31, (in millions) 2020 2019 Securities gains $ — $ — Securities losses (1 ) (8 ) Net securities losses $ (1 ) $ (8 ) The following table summarizes the amortized cost and fair values of debt securities by contractual maturity. Securities with multiple maturity dates are classified in the period of final maturity. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. (in millions) March 31, 2020 Amortized Cost Fair Value Contractual maturity Within one year $ 30 $ 31 After one year through five years 2,874 2,999 After five years through ten years 884 907 After ten years 8,845 9,104 Total investment securities $ 12,633 $ 13,041 Included in the contractual maturity distribution in the table above were residential mortgage-backed securities with a total amortized cost of $9.9 billion and a fair value of $10.2 billion . The actual cash flows of mortgage-backed securities may differ as borrowers of the underlying loans may exercise prepayment options. At March 31, 2020 , investment securities with a carrying value of $6.2 billion were pledged where permitted or required by law, including $5.5 billion pledged to the Federal Home Loan Bank (FHLB) as collateral for potential future borrowings of approximately $5.2 billion and $675 million to secure $510 million of liabilities, primarily public and other deposits of state and local government agencies as well as derivative instruments. For information on FHLB borrowings, refer to Note 7.

Credit Quality And Allowance Fo

Credit Quality And Allowance For Credit Losses	3 Months Ended
	Mar. 31, 2020
Credit Quality And Allowance For Credit Losses [Abstract]
Credit Quality And Allowance For Credit Losses	CREDIT QUALITY AND ALLOWANCE FOR CREDIT LOSSES The following table presents an aging analysis of the amortized cost basis of loans. Loans Past Due and Still Accruing (in millions) 30-59 Days 60-89 Days 90 Days or More Total Nonaccrual Loans Current Loans Total Loans March 31, 2020 Business loans: Commercial $ 224 $ 22 $ 42 $ 288 $ 173 $ 33,788 $ 34,249 Real estate construction: Commercial Real Estate business line (a) 4 1 — 5 — 3,341 3,346 Other business lines (b) — — — — — 410 410 Total real estate construction 4 1 — 5 — 3,751 3,756 Commercial mortgage: Commercial Real Estate business line (a) 1 — 8 9 3 2,167 2,179 Other business lines (b) 59 10 10 79 16 7,424 7,519 Total commercial mortgage 60 10 18 88 19 9,591 9,698 Lease financing — — — — 1 583 584 International 14 — 4 18 — 1,017 1,035 Total business loans 302 33 64 399 193 48,730 49,322 Retail loans: Residential mortgage 37 3 — 40 20 1,761 1,821 Consumer: Home equity 5 1 — 6 22 1,699 1,727 Other consumer 1 — — 1 — 587 588 Total consumer 6 1 — 7 22 2,286 2,315 Total retail loans 43 4 — 47 42 4,047 4,136 Total loans $ 345 $ 37 $ 64 $ 446 $ 235 $ 52,777 $ 53,458 December 31, 2019 Business loans: Commercial $ 27 $ 7 $ 17 $ 51 $ 148 $ 31,274 $ 31,473 Real estate construction: Commercial Real Estate business line (a) 6 — — 6 — 3,038 3,044 Other business lines (b) — 7 — 7 — 404 411 Total real estate construction 6 7 — 13 — 3,442 3,455 Commercial mortgage: Commercial Real Estate business line (a) 9 — — 9 2 2,165 2,176 Other business lines (b) 16 18 9 43 12 7,328 7,383 Total commercial mortgage 25 18 9 52 14 9,493 9,559 Lease financing 1 — — 1 — 587 588 International — 5 — 5 — 1,004 1,009 Total business loans 59 37 26 122 162 45,800 46,084 Retail loans: Residential mortgage 15 2 — 17 20 1,808 1,845 Consumer: Home equity 4 5 — 9 17 1,685 1,711 Other consumer 2 3 — 5 — 724 729 Total consumer 6 8 — 14 17 2,409 2,440 Total retail loans 21 10 — 31 37 4,217 4,285 Total loans $ 80 $ 47 $ 26 $ 153 $ 199 $ 50,017 $ 50,369 (a) Primarily loans to real estate developers. (b) Primarily loans secured by owner-occupied real estate. The following table presents loans by credit quality indicator and vintage year. Credit quality indicator is based on internal risk ratings assigned to each business loan at the time of approval and subjected to subsequent reviews, generally at least annually, and to pools of retail loans with similar risk characteristics. Vintage year is the year of origination or major modification. March 31, 2020 December 31, 2019 Vintage Year (in millions) 2020 2019 2018 2017 2016 Prior Revolvers Revolvers Converted to Term Total Total Business loans: Commercial: Pass (a) $ 634 $ 2,829 $ 2,069 $ 1,386 $ 636 $ 1,143 $ 23,528 $ 13 $ 32,238 $ 29,785 Special Mention (b) 12 106 72 57 41 47 627 — 962 841 Substandard (c) 3 109 122 24 41 32 544 1 876 699 Nonaccrual (d) 2 11 3 20 10 53 72 2 173 148 Total commercial 651 3,055 2,266 1,487 728 1,275 24,771 16 34,249 31,473 Real estate construction Pass (a) 98 709 1,140 812 527 220 217 — 3,723 3,424 Special Mention (b) — — — — — — 18 — 18 19 Substandard (c) — — 1 14 — — — — 15 12 Total real estate construction 98 709 1,141 826 527 220 235 — 3,756 3,455 Commercial mortgage Pass (a) 472 1,769 1,274 1,323 975 3,114 481 — 9,408 9,262 Special Mention (b) 6 46 18 13 27 50 5 — 165 159 Substandard (c) 2 7 — 11 8 78 — — 106 124 Nonaccrual (d) — — 2 1 3 13 — — 19 14 Total commercial mortgage 480 1,822 1,294 1,348 1,013 3,255 486 — 9,698 9,559 Lease financing Pass (a) 37 147 89 58 18 219 — — 568 579 Special Mention (b) — 6 3 2 2 — — — 13 7 Substandard (c) — 1 — 1 — — — — 2 2 Nonaccrual (d) 1 — — — — — — — 1 — Total lease financing 38 154 92 61 20 219 — — 584 588 International Pass (a) 228 185 161 34 1 74 306 — 989 972 Special Mention (b) — — 4 4 4 2 26 — 40 29 Substandard (c) — — 1 — — — 5 — 6 8 Total international 228 185 166 38 5 76 337 — 1,035 1,009 Total business loans 1,495 5,925 4,959 3,760 2,293 5,045 25,829 16 49,322 46,084 Table continues on the following page. March 31, 2020 December 31, 2019 Vintage Year (in millions) 2020 2019 2018 2017 2016 Prior Revolvers Revolvers Converted to Term Total Total Retail loans: Residential mortgage Pass (a) 136 260 170 340 285 606 — — 1,797 1,823 Special Mention (b) — — 4 — — — — — 4 2 Nonaccrual (d) — — 1 1 2 16 — — 20 20 Total residential mortgage 136 260 175 341 287 622 — — 1,821 1,845 Consumer: Home equity Pass (a) — — — — — 21 1,586 90 1,697 1,682 Special Mention (b) — — — — — — 1 — 1 1 Substandard (c) — — — — — — 4 3 7 11 Nonaccrual (d) — — — — — 1 15 6 22 17 Total home equity — — — — — 22 1,606 99 1,727 1,711 Other consumer Pass (a) 6 89 28 10 11 64 373 — 581 722 Special Mention (b) — — 1 — — — 6 — 7 6 Substandard (c) — — — — — — — — — 1 Total other consumer 6 89 29 10 11 64 379 — 588 729 Total consumer 6 89 29 10 11 86 1,985 99 2,315 2,440 Total retail loans 142 349 204 351 298 708 1,985 99 4,136 4,285 Total loans $ 1,637 $ 6,274 $ 5,163 $ 4,111 $ 2,591 $ 5,753 $ 27,814 $ 115 $ 53,458 $ 50,369 (a) Includes all loans not included in the categories of special mention, substandard or nonaccrual. (b) Special mention loans are accruing loans that have potential credit weaknesses that deserve management’s close attention, such as loans to borrowers who may be experiencing financial difficulties that may result in deterioration of repayment prospects from the borrower at some future date. This category is generally consistent with the "special mention" category as defined by regulatory authorities. (c) Substandard loans are accruing loans that have a well-defined weakness, or weaknesses, such as loans to borrowers who may be experiencing losses from operations or inadequate liquidity of a degree and duration that jeopardizes the orderly repayment of the loan. Substandard loans also are distinguished by the distinct possibility of loss in the future if these weaknesses are not corrected. This category is generally consistent with the "substandard" category as defined by regulatory authorities. (d) Nonaccrual loans are loans for which the accrual of interest has been discontinued. For further information regarding nonaccrual loans, refer to the Nonperforming Assets subheading in Note 1 - Basis of Presentation and Accounting Policies - on page F-51 in the Corporation's 2019 Annual Report. A significant majority of nonaccrual loans are generally consistent with the "substandard" category and the remainder are generally consistent with the "doubtful" category as defined by regulatory authorities. Loan interest receivable totaled $161 million and $172 million at March 31, 2020 and December 31, 2019 , respectively, and was included in accrued income and other assets on the Consolidated Balance Sheets. Substantially all individually evaluated loans are collateral-dependent and, at March 31, 2020 , consisted primarily of commercial and commercial mortgage loans. Collateral-dependent commercial loans were secured by oil and gas assets, accounts receivable, inventory and equipment, and collateral-dependent commercial mortgage loans were secured by commercial real estate assets. The most significant change in collateral values during the first quarter of 2020 was a decrease in the value of oil and gas assets related to supply/demand imbalances in the energy market. Allowance for Credit Losses The following table details the changes in the allowance for loan losses. 2020 2019 (in millions) Business Loans Retail Loans Total Business Loans Retail Loans Total Three Months Ended March 31 Balance at beginning of period $ 601 $ 36 $ 637 $ 627 $ 44 $ 671 Cumulative effect of change in accounting principle (42 ) 25 (17 ) — — — Loan charge-offs (87 ) (2 ) (89 ) (19 ) (1 ) (20 ) Recoveries on loans previously charged-off 5 — 5 8 1 9 Net loan charge-offs (82 ) (2 ) (84 ) (11 ) — (11 ) Provision for loan losses 384 (4 ) 380 (8 ) (5 ) (13 ) Balance at end of period $ 861 $ 55 $ 916 $ 608 $ 39 $ 647 As a percentage of total loans 1.75 % 1.35 % 1.71 % 1.33 % 0.88 % 1.29 % Changes in the allowance for credit losses on lending-related commitments, included in accrued expenses and other liabilities on the Consolidated Balance Sheets, are summarized in the following table. Three Months Ended March 31, (in millions) 2020 2019 Balance at beginning of period $ 31 $ 30 Provision for credit losses on lending-related commitments 31 — Balance at end of period $ 62 $ 30 Nonaccrual Loans The following table presents additional information regarding nonaccrual loans. No interest income was recognized on nonaccrual loans for the three months ended March 31, 2020 and 2019 , respectively. (in millions) Nonaccrual Loans with No Related Allowance Nonaccrual Loans with Related Allowance Total Nonaccrual Loans March 31, 2020 Business loans: Commercial $ 25 $ 148 $ 173 Commercial mortgage: Commercial Real Estate business line (a) 2 1 3 Other business lines (b) 3 13 16 Total commercial mortgage 5 14 19 Lease financing — 1 1 Total business loans 30 163 193 Retail loans: Residential mortgage 20 — 20 Consumer: Home equity 22 — 22 Total retail loans 42 — 42 Total nonaccrual loans $ 72 $ 163 $ 235 December 31, 2019 Business loans: Commercial $ 29 $ 119 $ 148 Commercial mortgage: Commercial Real Estate business line (a) 2 — 2 Other business lines (b) 1 11 12 Total commercial mortgage 3 11 14 Total business loans 32 130 162 Retail loans: Residential mortgage 20 — 20 Consumer: Home equity 17 — 17 Total retail loans 37 — 37 Total nonaccrual loans $ 69 $ 130 $ 199 (a) Primarily loans to real estate developers. (b) Primarily loans secured by owner-occupied real estate. Foreclosed Properties Foreclosed properties totaled $11 million at both March 31, 2020 and December 31, 2019 . There were no retail loans secured by residential real estate properties in process of foreclosure included in nonaccrual loans at March 31, 2020 and December 31, 2019 . Troubled Debt Restructurings The following table details the amortized cost basis at March 31, 2020 and 2019 of loans considered to be troubled debt restructurings (TDRs) that were restructured during the three-month periods ended March 31, 2020 and 2019 , by type of modification. In cases of loans with more than one type of modification, the loans were categorized based on the most significant modification. Principal Deferrals (a) (in millions) 2020 2019 Three Months Ended March 31, Business loans: Commercial $ 22 $ 12 Commercial mortgage: Other business lines (b) 2 1 Total loans $ 24 $ 13 (a) Primarily represents loan balances where terms were extended by more than an insignificant time period, typically more than 180 days, at or above contractual interest rates. Also includes commercial loans restructured in bankruptcy. (b) Primarily loans secured by owner-occupied real estate. The Corporation charges interest on principal balances outstanding during deferral periods. Additionally, none of the modifications involved forgiveness of principal. At both March 31, 2020 and December 31, 2019 , commitments to lend additional funds to borrowers whose terms have been modified in TDRs totaled $3 million . On an ongoing basis, the Corporation monitors the performance of modified loans to their restructured terms. The allowance for loan losses continues to be reassessed on the basis of an individual evaluation of the loan. The following table presents information regarding the amortized cost basis at March 31, 2020 and 2019 of loans modified by principal deferral during the twelve-month periods ended March 31, 2020 and 2019 . Principal Deferrals (in millions) 2020 2019 March 31 Business loans: Commercial $ 33 $ 26 Commercial mortgage: Other business lines (a) 2 2 Total business loans 35 28 Retail loans: Consumer: Home equity (b) — 1 Total loans $ 35 $ 29 (a) Primarily loans secured by owner-occupied real estate. (b) Includes bankruptcy loans for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt. During the twelve-month periods ended March 31, 2020 and 2019 , loans with a carrying value of $1 million and $4 million , respectively, were modified by interest rate reduction (reduced-rate loans). For principal deferrals, incremental deterioration in the credit quality of the loan, represented by a downgrade in the risk rating of the loan, for example, due to missed interest payments or a reduction of collateral value, is considered a subsequent default. For interest rate reductions, a subsequent payment default is defined in terms of delinquency, when a principal or interest payment is 90 days past due. Subsequent defaults of principal deferrals totaled $10 million in the three-month period ended March 31, 2020 , compared to none in the comparable period in 2019 . There were no subsequent defaults of interest rate reductions during either of the three-month periods ended March 31, 2020 and 2019

Derivative And Credit-Related F

Derivative And Credit-Related Financial Instruments	3 Months Ended
	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative And Credit-Related Financial Instruments	DERIVATIVE AND CREDIT-RELATED FINANCIAL INSTRUMENTS In the normal course of business, the Corporation enters into various transactions involving derivative and credit-related financial instruments to manage exposure to fluctuations in interest rate, foreign currency and other market risks and to meet the financing needs of customers (customer-initiated derivatives). These financial instruments involve, to varying degrees, elements of market and credit risk. Market and credit risk are included in the determination of fair value. Market risk is the potential loss that may result from movements in interest rates, foreign currency exchange rates or energy commodity prices that cause an unfavorable change in the value of a financial instrument. The Corporation manages this risk by establishing monetary exposure limits and monitoring compliance with those limits. Market risk inherent in interest rate and energy contracts entered into on behalf of customers is mitigated by taking offsetting positions, except in those circumstances when the amount, tenor and/or contract rate level results in negligible economic risk, whereby the cost of purchasing an offsetting contract is not economically justifiable. The Corporation mitigates most of the inherent market risk in foreign exchange contracts entered into on behalf of customers by taking offsetting positions and manages the remainder through individual foreign currency position limits and aggregate value-at-risk limits. These limits are established annually and positions are monitored quarterly. Market risk inherent in derivative instruments held or issued for risk management purposes is typically offset by changes in the fair value of the assets or liabilities being hedged. Credit risk is the possible loss that may occur in the event of nonperformance by the counterparty to a financial instrument. The Corporation attempts to minimize credit risk arising from customer-initiated derivatives by evaluating the creditworthiness of each customer, adhering to the same credit approval process used for traditional lending activities and obtaining collateral as deemed necessary. Derivatives with dealer counterparties are either cleared through a clearinghouse or settled directly with a single counterparty. For derivatives settled directly with dealer counterparties, the Corporation utilizes counterparty risk limits and monitoring procedures as well as master netting arrangements and bilateral collateral agreements to facilitate the management of credit risk. Master netting arrangements effectively reduce credit risk by permitting settlement of positive and negative positions and offset cash collateral held with the same counterparty on a net basis. Bilateral collateral agreements require daily exchange of cash or highly rated securities issued by the U.S. Treasury or other U.S. government entities to collateralize amounts due to either party. At March 31, 2020 , counterparties with bilateral collateral agreements deposited $427 million of cash with the Corporation to secure the fair value of contracts in an unrealized gain position, and the Corporation had pledged $59 million of marketable investment securities and posted $26 million of cash as collateral for contracts in an unrealized loss position. For those counterparties not covered under bilateral collateral agreements, collateral is obtained, if deemed necessary, based on the results of management’s credit evaluation of the counterparty. Collateral varies, but may include cash, investment securities, accounts receivable, equipment or real estate. Included in the fair value of derivative instruments are credit valuation adjustments reflecting counterparty credit risk. These adjustments are determined by applying a credit spread for the counterparty or the Corporation, as appropriate, to the total expected exposure of the derivative. There were no derivative instruments with credit-risk-related contingent features that were in a liability position at March 31, 2020 . Derivative Instruments Derivative instruments utilized by the Corporation are negotiated over-the-counter and primarily include swaps, caps and floors, forward contracts and options, each of which may relate to interest rates, energy commodity prices or foreign currency exchange rates. Swaps are agreements in which two parties periodically exchange cash payments based on specified indices applied to a specified notional amount until a stated maturity. Caps and floors are agreements which entitle the buyer to receive cash payments based on the difference between a specified reference rate or price and an agreed strike rate or price, applied to a specified notional amount until a stated maturity. Forward contracts are over-the-counter agreements to buy or sell an asset at a specified future date and price. Options are similar to forward contracts except the purchaser has the right, but not the obligation, to buy or sell the asset during a specified period or at a specified future date. Over-the-counter contracts are tailored to meet the needs of the counterparties involved and, therefore, contain a greater degree of credit risk and liquidity risk than exchange-traded contracts, which have standardized terms and readily available price information. The Corporation reduces exposure to market and liquidity risks from over-the-counter derivative instruments entered into for risk management purposes, and transactions entered into to mitigate the market risk associated with customer-initiated transactions, by taking offsetting positions with investment grade domestic and foreign financial institutions and subjecting counterparties to credit approvals, limits and collateral monitoring procedures similar to those used in making other extensions of credit. In addition, certain derivative contracts executed bilaterally with a dealer counterparty in the over-the-counter market are cleared through a clearinghouse, whereby the clearinghouse becomes the counterparty to the transaction. The following table presents the composition of the Corporation’s derivative instruments held or issued for risk management purposes or in connection with customer-initiated and other activities at March 31, 2020 and December 31, 2019 . The table excludes commitments and warrants accounted for as derivatives. March 31, 2020 December 31, 2019 Fair Value Fair Value (in millions) Notional/ Contract Amount (a) Gross Derivative Assets Gross Derivative Liabilities Notional/ Contract Amount (a) Gross Derivative Assets Gross Derivative Liabilities Risk management purposes Derivatives designated as hedging instruments Interest rate contracts: Swaps - fair value - receive fixed/pay floating $ 3,325 $ — $ — $ 3,325 $ — $ — Swaps - cash flow - receive fixed/pay floating 5,550 — — 4,550 — — Derivatives used as economic hedges Foreign exchange contracts: Spot, forwards and swaps 366 3 2 330 — 2 Total risk management purposes 9,241 3 2 8,205 — 2 Customer-initiated and other activities Interest rate contracts: Caps and floors written 681 — — 671 — — Caps and floors purchased 681 — — 671 — — Swaps 19,754 605 70 16,485 211 39 Total interest rate contracts 21,116 605 70 17,827 211 39 Energy contracts: Caps and floors written 439 1 76 477 — 23 Caps and floors purchased 439 76 1 477 23 — Swaps 1,966 382 377 2,135 73 69 Total energy contracts 2,844 459 454 3,089 96 92 Foreign exchange contracts: Spot, forwards, options and swaps 1,531 31 25 1,013 10 8 Total customer-initiated and other activities 25,491 1,095 549 21,929 317 139 Total gross derivatives $ 34,732 $ 1,098 $ 551 $ 30,134 $ 317 $ 141 Amounts offset in the Consolidated Balance Sheets: Netting adjustment - Offsetting derivative assets/liabilities (55 ) (55 ) (63 ) (63 ) Netting adjustment - Cash collateral received/posted (424 ) (23 ) (11 ) (12 ) Net derivatives included in the Consolidated Balance Sheets (b) 619 473 243 66 Amounts not offset in the Consolidated Balance Sheets: Marketable securities pledged under bilateral collateral agreements — (54 ) — (21 ) Net derivatives after deducting amounts not offset in the Consolidated Balance Sheets $ 619 $ 419 $ 243 $ 45 (a) Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Balance Sheets. (b) Net derivative assets are included in accrued income and other assets and net derivative liabilities are included in accrued expenses and other liabilities on the Consolidated Balance Sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and credit risk of the Corporation. The fair value of net derivative assets included credit valuation adjustments for counterparty credit risk of $22 million and $9 million at March 31, 2020 and December 31, 2019 , respectively. Risk Management The Corporation's derivative instruments used for managing interest rate risk currently comprise swaps converting fixed-rate long-term debt to variable rates and variable-rate loans to fixed rates. The following table details the effects of fair value hedging on the Consolidated Statements of Comprehensive Income. Interest on Medium- and Long-Term Debt Three Months Ended March 31, (in millions) 2020 2019 Total interest on medium-and long-term debt (a) $ 40 $ 51 Fair value hedging relationships: Interest rate contracts: Hedged items 30 26 Derivatives designated as hedging instruments (6 ) 1 (a) Includes the effects of hedging. For information on accumulated net gains on cash flow hedges, refer to Note 8. The following table summarizes the expected weighted average remaining maturity of the notional amount of risk management interest rate swaps, the carrying amount of the related hedged items and the weighted average interest rates associated with amounts expected to be received or paid on interest rate swap agreements as of March 31, 2020 and December 31, 2019 . Cash flow swaps - receive fixed/pay floating rate on variable-rate loans: (dollar amounts in millions) March 31, 2020 December 31, 2019 Derivative Notional Amount $ 5,550 $ 4,550 Weighted Average: Remaining maturity (in years) 3.0 3.0 Receive rate 1.87 % 1.94 % Pay rate (a) 1.58 1.71 (a) Variable rates paid on receive fixed swaps designated as cash flow hedges are based on one-month LIBOR rates in effect at March 31, 2020 and December 31, 2019 . Fair value swaps - receive fixed/pay floating rate on medium- and long-term debt: (dollar amounts in millions) March 31, 2020 December 31, 2019 Derivative Notional Amount $ 3,325 $ 3,325 Carrying value of hedged items (a) 3,634 3,469 Weighted Average: Remaining maturity (in years) 4.3 4.6 Receive rate 3.44 % 3.44 % Pay rate (b) 2.32 2.80 (a) Included $ 310 million and $ 146 million of cumulative hedging adjustments at March 31, 2020 and December 31, 2019 , respectively, which included $ 6 million and $ 7 million , respectively, of hedging adjustment on a discontinued hedging relationship. (b) Variable rates paid on receive fixed swaps designated as fair value hedges are based on one- and six-month LIBOR rates in effect at March 31, 2020 and December 31, 2019 . Foreign exchange rate risk arises from changes in the value of certain assets and liabilities denominated in foreign currencies. The Corporation employs spot and forward contracts in addition to swap contracts to manage exposure to these and other risks. These instruments are used as economic hedges, and net gains or losses are included in other noninterest income in the Consolidated Statements of Comprehensive Income. Customer-Initiated and Other The Corporation enters into derivative transactions at the request of customers and generally takes offsetting positions with dealer counterparties to mitigate the inherent market risk. Income primarily results from the spread between the customer derivative and the offsetting dealer position. For customer-initiated foreign exchange contracts where offsetting positions have not been taken, the Corporation manages the remaining inherent market risk through individual foreign currency position limits and aggregate value-at-risk limits. These limits are established annually and reviewed quarterly. For those customer-initiated derivative contracts which were not offset or where the Corporation holds a position within the limits described above, the Corporation recognized no net gains or losses in other noninterest income in the Consolidated Statements of Comprehensive Income for both the three-month periods ended March 31, 2020 and 2019 . Fair values of customer-initiated and other derivative instruments represent the net unrealized gains or losses on such contracts and are recorded in the Consolidated Balance Sheets. Changes in fair value are recognized in the Consolidated Statements of Comprehensive Income. The net gains recognized in income on customer-initiated derivative instruments, net of the impact of offsetting positions, were as follows . Three Months Ended March 31, (in millions) Location of Gain 2020 2019 Interest rate contracts Other noninterest income $ 8 $ 6 Energy contracts Other noninterest income 1 1 Foreign exchange contracts Foreign exchange income 11 11 Total $ 20 $ 18 Credit-Related Financial Instruments The Corporation issues off-balance sheet financial instruments in connection with commercial and consumer lending activities. The Corporation’s credit risk associated with these instruments is represented by the contractual amounts indicated in the following table. (in millions) March 31, 2020 December 31, 2019 Unused commitments to extend credit: Commercial and other $ 21,456 $ 23,681 Bankcard, revolving check credit and home equity loan commitments 3,170 3,180 Total unused commitments to extend credit $ 24,626 $ 26,861 Standby letters of credit $ 3,208 $ 3,320 Commercial letters of credit 35 18 The Corporation maintains an allowance to cover current expected credit losses on lending-related commitments, including unused commitments to extend credit, letters of credit and financial guarantees. The allowance for credit losses on lending-related commitments, included in accrued expenses and other liabilities on the Consolidated Balance Sheets, was $62 million and $31 million at March 31, 2020 and December 31, 2019 , respectively. Unused Commitments to Extend Credit Commitments to extend credit are legally binding agreements to lend to a customer, provided there is no violation of any condition established in the contract. These commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since many commitments expire without being drawn upon, the total contractual amount of commitments does not necessarily represent future cash requirements of the Corporation. Commercial and other unused commitments are primarily variable rate commitments. The allowance for credit losses on lending-related commitments included $51 million at March 31, 2020 and $25 million at December 31, 2019 for current expected credit losses on the Corporation’s unused commitments to extend credit. Standby and Commercial Letters of Credit Standby letters of credit represent conditional obligations of the Corporation which guarantee the performance of a customer to a third party. Standby letters of credit are primarily issued to support public and private borrowing arrangements, including commercial paper, bond financing and similar transactions. Commercial letters of credit are issued to finance foreign or domestic trade transactions. These contracts expire in decreasing amounts through the year 2028 . The Corporation may enter into participation arrangements with third parties that effectively reduce the maximum amount of future payments which may be required under standby and commercial letters of credit. These risk participations covered $160 million and $161 million , respectively, of the $3.2 billion and $3.3 billion standby and commercial letters of credit outstanding at March 31, 2020 and December 31, 2019 , respectively. The carrying value of the Corporation’s standby and commercial letters of credit, included in accrued expenses and other liabilities on the Consolidated Balance Sheets, totaled $33 million at March 31, 2020 , including $23 million in deferred fees and $10 million in the allowance for credit losses on lending-related commitments. At December 31, 2019 , the comparable amounts were $32 million , $26 million and $6 million , respectively. The following table presents a summary of criticized standby and commercial letters of credit at March 31, 2020 and December 31, 2019 . The Corporation's criticized list is generally consistent with the Special Mention, Substandard and Doubtful categories defined by regulatory authorities. The Corporation manages credit risk through underwriting, periodically reviewing and approving its credit exposures using Board committee approved credit policies and guidelines. (dollar amounts in millions) March 31, 2020 December 31, 2019 Total criticized standby and commercial letters of credit $ 50 $ 44 As a percentage of total outstanding standby and commercial letters of credit 1.5 % 1.3 % Other Credit-Related Financial Instruments The Corporation enters into credit risk participation agreements, under which the Corporation assumes credit exposure associated with a borrower’s performance related to certain interest rate derivative contracts. The Corporation is not a party to the interest rate derivative contracts and only enters into these credit risk participation agreements in instances in which the Corporation is also a party to the related loan participation agreements for such borrowers. The Corporation manages credit risk on credit risk participation agreements by monitoring the creditworthiness of the borrowers, based on the normal credit review process as if the Corporation had entered into the derivative instruments directly with the borrowers. The notional amount of such credit risk participation agreements reflects the pro-rata share of the derivative instrument, consistent with the Corporation's share of the related participated loan. As of March 31, 2020 and December 31, 2019 , the total notional amount of the credit risk participation agreements was approximately $807 million and $786 million , respectively, and the fair value was insignificant for both periods. The maximum estimated exposure to these agreements, as measured by projecting a maximum value of the guaranteed derivative instruments, assuming 100 percent default by all obligors on the maximum values, was $50 million and $20 million at March 31, 2020 and December 31, 2019 , respectively. In the event of default, the lead bank has the ability to liquidate the assets of the borrower, in which case the lead bank would be required to return a percentage of the recouped assets to the participating banks. As of March 31, 2020 , the weighted average remaining maturity of outstanding credit risk participation agreements was 3.4 years.

Variable Interest Entities (VIE

Variable Interest Entities (VIEs)	3 Months Ended
	Mar. 31, 2020
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Variable Interest Entities (VIEs)	VARIABLE INTEREST ENTITIES (VIEs) The Corporation evaluates its interest in certain entities to determine if these entities meet the definition of a VIE and whether the Corporation is the primary beneficiary and should consolidate the entity based on the variable interests it held both at inception and when there is a change in circumstances that requires a reconsideration. The Corporation holds ownership interests in funds in the form of limited partnerships or limited liability companies (LLCs) investing in affordable housing projects that qualify for the low-income housing tax credit (LIHTC). The Corporation also directly invests in limited partnerships and LLCs which invest in community development projects, which generate similar tax credits to investors (other tax credit entities). As an investor, the Corporation obtains income tax credits and deductions from the operating losses of these tax credit entities. These tax credit entities meet the definition of a VIE; however, the Corporation is not the primary beneficiary of the entities, as the general partner or the managing member has both the power to direct the activities that most significantly impact the economic performance of the entities and the obligation to absorb losses or the right to receive benefits that could be significant to the entities. The Corporation accounts for its interests in LIHTC entities using the proportional amortization method. Ownership interests in other tax credit entities are accounted for under either the cost or equity method. Exposure to loss as a result of the Corporation's involvement in LIHTC entities at March 31, 2020 was limited to $453 million. There was no exposure to loss as a result of the Corporation's involvement in other tax credit entities at March 31, 2020. Investment balances, including all legally binding commitments to fund future investments, are included in accrued income and other assets on the Consolidated Balance Sheets. A liability is recognized in accrued expenses and other liabilities on the Consolidated Balance Sheets for all legally binding unfunded commitments to fund tax credit entities ( $167 million at March 31, 2020 ). Amortization and other write-downs of LIHTC investments are presented on a net basis as a component of the provision for income taxes on the Consolidated Statements of Comprehensive Income, while amortization and write-downs of other tax credit investments are recorded in other noninterest income. The income tax credits and deductions are recorded as a reduction of income tax expense and a reduction of federal income taxes payable. The Corporation provided no financial or other support that was not contractually required to any of the above VIEs during the three months ended March 31, 2020 and 2019 . The following table summarizes the impact of these tax credit entities on the Corporation’s Consolidated Statements of Comprehensive Income. Three Months Ended March 31, (in millions) 2020 2019 Other noninterest income: Amortization of other tax credit investments $ — $ 1 Provision for income taxes: Amortization of LIHTC investments 17 15 Low income housing tax credits (16 ) (15 ) Other tax benefits related to tax credit entities (4 ) (3 ) Total provision for income taxes $ (3 ) $ (3 ) For further information on the Corporation’s consolidation policy, see Note 1 to the consolidated financial statements in the Corporation's 2019 Annual Report.

Medium- And Long-Term Debt

Medium- And Long-Term Debt	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Medium- And Long-Term Debt	MEDIUM- AND LONG-TERM DEBT Medium- and long-term debt is summarized as follows: (in millions) March 31, 2020 December 31, 2019 Parent company Subordinated notes: 3.80% subordinated notes due 2026 (a) $ 282 $ 264 Medium- and long-term notes: 3.70% notes due 2023 (a) 917 884 4.00% notes due 2029 (a) 642 587 Total medium- and long-term notes 1,559 1,471 Total parent company 1,841 1,735 Subsidiaries Subordinated notes: 4.00% subordinated notes due 2025 (a) 381 360 7.875% subordinated notes due 2026 (a) 213 202 Total subordinated notes 594 562 Medium- and long-term notes: 2.50% notes due 2020 (a) (b) 675 674 2.50% notes due 2024 (a) 524 498 Total medium- and long-term notes 1,199 1,172 Federal Home Loan Bank (FHLB) advances: Floating-rate based on FHLB auction rate due 2026 2,800 2,800 Floating-rate based on FHLB auction rate due 2028 1,000 1,000 Total FHLB advances 3,800 3,800 Total subsidiaries 5,593 5,534 Total medium- and long-term debt $ 7,434 $ 7,269 (a) The fixed interest rates on these notes have been swapped to a variable rate and designated in a hedging relationship. Accordingly, carrying value has been adjusted to reflect the change in the fair value of the debt as a result of changes in the benchmark rate. (b) Due on June 2, 2020. Subordinated notes with remaining maturities greater than one year qualify as Tier 2 capital. Comerica Bank (the Bank), a wholly-owned subsidiary of the Corporation, is a member of the FHLB, which provides short- and long-term funding to its members through advances collateralized by real estate-related assets. The interest rates on the FHLB advances resets between four and eight weeks, based on the FHLB auction rate. At March 31, 2020 , the weighted-average rate on the FHLB advances was 0.92% . Each note may be prepaid in full, without penalty, at each scheduled reset date. Borrowing capacity is contingent on the amount of collateral available to be pledged to the FHLB. At March 31, 2020 , $ 17.6 billion of real estate-related loans and $5.5 billion of investment securities were pledged to the FHLB as collateral for outstanding short- and long-term advances of $750 million and $3.8 billion , respectively, with an additional capacity for potential future borrowings of approximately $9.9 billion . Unamortized debt issuance costs deducted from the carrying amount of medium- and long-term debt totaled $11 million at March 31, 2020 and $12 million at December 31, 2019 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Loss	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The following table presents a reconciliation of the changes in the components of accumulated other comprehensive income (loss) and details the components of other comprehensive income (loss) for the three months ended March 31, 2020 and 2019 , including the amount of income tax expense (benefit) allocated to each component of other comprehensive income (loss). Three Months Ended March 31, (in millions) 2020 2019 Accumulated net unrealized gains (losses) on investment securities: Balance at beginning of period, net of tax $ 65 $ (138 ) Net unrealized holding gains arising during the period 323 109 Less: Provision for income taxes 76 25 Net unrealized holding gains arising during the period, net of tax 247 84 Less: Net realized losses included in net securities losses — (8 ) Less: Benefit for income taxes — (2 ) Reclassification adjustment for net securities losses included in net income, net of tax — (6 ) Change in net unrealized gains on investment securities, net of tax 247 90 Balance at end of period, net of tax $ 312 $ (48 ) Accumulated net gains on cash flow hedges: Balance at beginning of period, net of tax $ 34 $ — Net cash flow hedge gains arising during the period 205 4 Less: Provision for income taxes 48 1 Change in net cash flow hedge gains arising during the period, net of tax 157 3 Less: Net cash flow hedge gains included in interest and fees on loans 3 — Less: Provision for income taxes 1 — Reclassification adjustment for net cash flow hedge gains included in net income, net of tax 2 — Change in net cash flow hedge gains, net of tax 155 3 Balance at end of period, net of tax (a) $ 189 $ 3 Accumulated defined benefit pension and other postretirement plans adjustment: Balance at beginning of period, net of tax $ (334 ) $ (471 ) Amortization of actuarial net loss 16 11 Amortization of prior service credit (7 ) (7 ) Amounts recognized in other noninterest expenses 9 4 Less: Provision for income taxes 2 1 Change in defined benefit pension and other postretirement plans adjustment, net of tax 7 3 Balance at end of period, net of tax $ (327 ) $ (468 ) Total accumulated other comprehensive income (loss) at end of period, net of tax $ 174 $ (513 ) (a) The Corporation expects to reclassify $66 million of net gains, net of tax, from accumulated other comprehensive income to earnings over the next twelve months if interest yield curves and notional amounts remain at March 31, 2020 levels.

Net (Loss) Income Per Common Sh

Net (Loss) Income Per Common Share	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Net (Loss) Income Per Common Share	NET (LOSS) INCOME PER COMMON SHARE Basic and diluted net (loss) income per common share are presented in the following table. Three Months Ended March 31, (in millions, except per share data) 2020 2019 Basic and diluted Net (loss) income $ (65 ) $ 339 Less: Income allocated to participating securities — 2 Net (loss) income attributable to common shares $ (65 ) $ 337 Basic average common shares 141 158 Basic net (loss) income per common share $ (0.46 ) $ 2.14 Basic average common shares 141 158 Dilutive common stock equivalents: Net effect of the assumed exercise of stock awards — 2 Diluted average common shares 141 160 Diluted net (loss) income per common share $ (0.46 ) $ 2.11 Average shares related to stock awards excluded from the calculation of diluted net (loss) income per share: Exercise price greater than average market price of common shares for the period 1.2 0.4 Anti-dilutive (a) 2.6 — (a) Average exercise price less than average market price of common shares for period; however, anti-dilutive due to net loss during the period.

Employee Benefit Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS Net periodic defined benefit cost (credit) is comprised of service cost and other components of net benefit cost (credit). Service cost is included in salaries and benefits expense and other components of net benefit cost (credit) are included in other noninterest expenses on the Consolidated Statements of Comprehensive Income. For further information on the Corporation's employee benefit plans, refer to Note 17 to the consolidated financial statements in the Corporation's 2019 Annual Report. The components of net periodic benefit cost (credit) for the Corporation's qualified pension plan, non-qualified pension plan and postretirement benefit plan are as follows. Qualified Defined Benefit Pension Plan Three Months Ended March 31, (in millions) 2020 2019 Service cost $ 8 $ 8 Other components of net benefit credit: Interest cost 18 20 Expected return on plan assets (43 ) (42 ) Amortization of prior service credit (5 ) (5 ) Amortization of net loss 14 9 Total other components of net benefit credit (16 ) (18 ) Net periodic defined benefit credit $ (8 ) $ (10 ) Non-Qualified Defined Benefit Pension Plan Three Months Ended March 31, (in millions) 2020 2019 Service cost $ 1 $ 1 Other components of net benefit cost: Interest cost 2 2 Amortization of prior service credit (2 ) (2 ) Amortization of net loss 2 2 Total other components of net benefit cost 2 2 Net periodic defined benefit cost $ 3 $ 3 Postretirement Benefit Plan Three Months Ended March 31, (in millions) 2020 2019 Other components of net benefit credit: Interest cost $ — $ 1 Expected return on plan assets — (1 ) Net periodic defined benefit credit $ — $ —

Income Taxes And Tax-Related It

Income Taxes And Tax-Related Items	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes and Tax-Related Items	INCOME TAXES AND TAX-RELATED ITEMS At March 31, 2020 , net unrecognized tax benefits were $19 million , compared to $17 million at December 31, 2019 . The Corporation anticipates that it is reasonably possible that final settlement of federal and state tax issues will not result in a change to net unrecognized tax benefits within the next twelve months. Included in accrued expenses and other liabilities on the Consolidated Balance Sheets was a liability for tax-related interest and penalties of $6 million and $8 million on March 31, 2020 and December 31, 2019 , respectively. Net deferred tax liabilities were $13 million at March 31, 2020 , compared to net deferred tax assets of $42 million at December 31, 2019 , primarily driven by increases to deferred tax liabilities related to unrealized gains on investment securities available-for-sale and net hedging gains, partially offset by increases to deferred tax assets related to the allowance for loan losses and allowance for depreciation. Included in deferred tax assets at both March 31, 2020 and December 31, 2019 were $3 million of state net operating loss carryforwards, which expire between 2020 and 2029 . The Corporation believes that it is more likely than not that the benefit from certain of these state net operating loss carryforwards will not be realized and, accordingly, maintained a valuation allowance of $3 million at both March 31, 2020 and December 31, 2019 . The determination regarding valuation allowance was based on evidence of loss carryback capacity, projected future reversals of existing taxable temporary differences to absorb the deferred tax assets and assumptions made regarding future events. In the ordinary course of business, the Corporation enters into certain transactions that have tax consequences. From time to time, the Internal Revenue Service (IRS) or other tax jurisdictions may review and/or challenge specific interpretive tax positions taken by the Corporation with respect to those transactions. The Corporation believes its tax returns were filed based upon applicable statutes, regulations and case law in effect at the time of the transactions. The IRS or other tax jurisdictions, an administrative authority or a court, if presented with the transactions, could disagree with the Corporation’s interpretation of the tax law. Based on current knowledge and probability assessment of various potential outcomes, the Corporation believes that current tax reserves are adequate, and the amount of any potential incremental liability arising is not expected to have a material adverse effect on the Corporation’s consolidated financial condition or results of operations. Probabilities and outcomes are reviewed as events unfold, and adjustments to the reserves are made when necessary.

Contingent Liabilities

Contingent Liabilities	3 Months Ended
	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Contingent Liabilities	CONTINGENT LIABILITIES Legal Proceedings As previously reported in the Corporation's Form 10-K for the year ended December 31, 2019 , Comerica Bank, a wholly-owned subsidiary of the Corporation, was named in November 2011 as a third-party defendant in Butte Local Development v. Masters Group v. Comerica Bank (the case), for lender liability. The case was initially tried in January 2014, in the Montana Second District Judicial Court for Silver Bow County in Butte, Montana. On January 17, 2014 , a jury found for Masters, resulting in an award against the Bank. On July 1, 2015, after an appeal filed by the Bank, the Montana Supreme Court reversed the judgment against the Bank and remanded the case for a new trial with instructions that Michigan contract law should apply and dismissing all other claims. In January 2017, the case was retried, without a jury, in the Second District Court, Silver Bow County, Montana. In November 2019, the court found the Bank breached its forbearance agreement. On January 17, 2020, the court conducted a hearing on the amount of costs and interest that Masters is entitled to recover. The court also heard argument on whether Masters is entitled to attorneys' fees, and if so how much. Its decision is pending. The Bank is considering its options, including additional appeals. Management believes that current reserves related to this case are adequate in the event of an adverse outcome. The Corporation and certain of its subsidiaries are subject to various other pending or threatened legal proceedings arising out of the normal course of business or operations. The Corporation believes it has meritorious defenses to the claims asserted against it in its other currently outstanding legal proceedings and, with respect to such legal proceedings, intends to continue to defend itself vigorously, litigating or settling cases according to management’s judgment as to what is in the best interests of the Corporation and its shareholders. Settlement may result from the Corporation's determination that it may be more prudent financially to settle, rather than litigate, and should not be regarded as an admission of liability. On at least a quarterly basis, the Corporation assesses its potential liabilities and contingencies in connection with outstanding legal proceedings utilizing the latest information available. On a case-by-case basis, reserves are established for those legal claims for which it is probable that a loss will be incurred either as a result of a settlement or judgment, and the amount of such loss can be reasonably estimated. The actual costs of resolving these claims may be substantially higher or lower than the amounts reserved. Based on current knowledge, and after consultation with legal counsel, management believes current reserves are adequate, and the amount of any incremental liability arising from these matters is not expected to have a material adverse effect on the Corporation’s consolidated financial condition, results of operations or cash flows. Legal fees of $2 million and $1 million were included in other noninterest expenses on the Consolidated Statements of Comprehensive Income for the three-month periods ended March 31, 2020 and 2019 , respectively. For matters where a loss is not probable, the Corporation has not established legal reserves. The Corporation believes the estimate of the aggregate range of reasonably possible losses, in excess of reserves established, for all legal proceedings in which it is involved is from zero to approximately $45 million at March 31, 2020 . This estimated aggregate range of reasonably possible losses is based upon currently available information for those proceedings in which the Corporation is involved, taking into account the Corporation’s best estimate of such losses for those cases for which such estimate can be made. For certain cases, the Corporation does not believe that an estimate can currently be made. The Corporation’s estimate involves significant judgment, given the varying stages of the proceedings (including the fact many are currently in preliminary stages), the existence in certain proceedings of multiple defendants (including the Corporation) whose share of liability has yet to be determined, the numerous yet-unresolved issues in many of the proceedings (including issues regarding class certification and the scope of many of the claims) and the attendant uncertainty of the various potential outcomes of such proceedings. Accordingly, the Corporation’s estimate will change from time to time, and actual losses may be more or less than the current estimate. In the event of unexpected future developments, it is possible the ultimate resolution of these matters, if unfavorable, may be material to the Corporation's consolidated financial condition, results of operations or cash flows. For information regarding income tax contingencies, refer to Note 11 .

Business Segment Information

Business Segment Information	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Business Segment Information	BUSINESS SEGMENT INFORMATION The Corporation has strategically aligned its operations into three major business segments: the Business Bank, the Retail Bank and Wealth Management. These business segments are differentiated based on the type of customer and the related products and services provided. In addition to the three major business segments, the Finance Division is also reported as a segment. Business segment results are produced by the Corporation’s internal management accounting system. This system measures financial results based on the internal business unit structure of the Corporation. The performance of the business segments is not comparable with the Corporation's consolidated results and is not necessarily comparable with similar information for any other financial institution. Additionally, because of the interrelationships of the various segments, the information presented is not indicative of how the segments would perform if they operated as independent entities. The management accounting system assigns balance sheet and income statement items to each business segment using certain methodologies, which are regularly reviewed and refined. From time to time, the Corporation may make reclassifications among the segments to more appropriately reflect management's current view of the segments, and methodologies may be modified as the management accounting system is enhanced and changes occur in the organizational structure and/or product lines. For comparability purposes, amounts in all periods are based on business unit structure and methodologies in effect at March 31, 2020 . The following discussion provides information about the activities of each business segment. A discussion of the financial results and the factors impacting performance can be found in the section entitled "Business Segments" in the financial review. The Business Bank meets the needs of small and middle market businesses, multinational corporations and governmental entities by offering various products and services including commercial loans and lines of credit, deposits, cash management, capital market products, international trade finance, letters of credit, foreign exchange management services and loan syndication services. The Retail Bank includes a full range of personal financial services, consisting of consumer lending, consumer deposit gathering and mortgage loan origination. This business segment offers a variety of consumer products including deposit accounts, installment loans, credit cards, student loans, home equity lines of credit and residential mortgage loans. Wealth Management offers products and services consisting of fiduciary services, private banking, retirement services, investment management and advisory services, investment banking and brokerage services. This business segment also offers the sale of annuity products, as well as life, disability and long-term care insurance products. The Finance segment includes the Corporation’s securities portfolio and asset and liability management activities. This segment is responsible for managing the Corporation’s funding, liquidity and capital needs, performing interest sensitivity analysis and executing various strategies to manage the Corporation’s exposure to liquidity, interest rate risk and foreign exchange risk. The Other category includes the income and expense impact of equity and cash, tax benefits not assigned to specific business segments, charges of an unusual or infrequent nature that are not reflective of the normal operations of the business segments and miscellaneous other expenses of a corporate nature. For further information on the methodologies which form the basis for these results refer to Note 22 to the consolidated financial statements in the Corporation's 2019 Annual Report. Business segment financial results are as follows: Business Retail Wealth Management Finance Other Total (dollar amounts in millions) Three Months Ended March 31, 2020 Earnings summary: Net interest income (expense) $ 380 $ 125 $ 41 $ (44 ) $ 11 $ 513 Provision for credit losses 396 3 12 — — 411 Noninterest income 127 28 70 14 (2 ) 237 Noninterest expenses 194 149 72 — 10 425 (Benefit) provision for income taxes (20 ) — 6 (8 ) 1 (a) (21 ) Net (loss) income $ (63 ) $ 1 $ 21 $ (22 ) $ (2 ) $ (65 ) Net credit-related charge-offs $ 83 $ 1 $ — $ — $ — $ 84 Selected average balances: Assets $ 44,254 $ 2,864 $ 5,078 $ 14,285 $ 6,784 $ 73,265 Loans 42,593 2,075 4,936 — — 49,604 Deposits 30,230 21,195 4,025 1,136 182 56,768 Statistical data: Return on average assets (b) (0.58 )% 0.03 % 1.69 % n/m n/m (0.35 )% Efficiency ratio (c) 38.47 96.03 64.28 n/m n/m 56.57 Three Months Ended March 31, 2019 Earnings summary: Net interest income (expense) $ 412 $ 146 $ 48 $ (15 ) $ 15 $ 606 Provision for credit losses (6 ) (4 ) (5 ) — 2 (13 ) Noninterest income 136 31 64 3 4 238 Noninterest expenses 198 145 72 — 18 433 Provision (benefit) for income taxes 82 8 11 (4 ) (12 ) (a) 85 Net income (loss) $ 274 $ 28 $ 34 $ (8 ) $ 11 $ 339 Net credit-related charge-offs (recoveries) $ 12 $ — $ (1 ) $ — $ — $ 11 Selected average balances: Assets $ 43,909 $ 2,812 $ 5,174 $ 13,585 $ 4,291 $ 69,771 Loans 42,538 2,103 5,036 — — 49,677 Deposits 28,463 20,470 3,801 1,130 132 53,996 Statistical data: Return on average assets (b) 2.53 % 0.54 % 2.67 % n/m n/m 1.97 % Efficiency ratio (c) 36.24 81.34 64.42 n/m n/m 50.81 (a) Included discrete tax benefits of $3 million and $11 million for the three months ended March 31, 2020 and 2019 , respectively. (b) Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (c) Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net (losses) gains from securities and a derivative contract tied to the conversion rate of Visa Class B shares. n/m – not meaningful The Corporation operates in three primary markets - Texas, California and Michigan, as well as in Arizona and Florida, with select businesses operating in several other states and in Canada and Mexico. The Corporation produces market segment results for the Corporation’s three primary geographic markets as well as Other Markets. Other Markets includes Florida, Arizona, the International Finance division and businesses with a national perspective. The Finance & Other category includes the Finance segment and the Other category as previously described. Market segment results are provided as supplemental information to the business segment results and may not meet all operating segment criteria as set forth in GAAP. For comparability purposes, amounts in all periods are based on market segments and methodologies in effect at March 31, 2020 . A discussion of the financial results and the factors impacting performance can be found in the section entitled "Market Segments" in the financial review. Market segment financial results are as follows: Michigan California Texas Other Finance Total (dollar amounts in millions) Three Months Ended March 31, 2020 Earnings summary: Net interest income (expense) $ 163 $ 182 $ 115 $ 86 $ (33 ) $ 513 Provision for credit losses 24 51 290 46 — 411 Noninterest income 72 36 30 87 12 237 Noninterest expenses 140 98 84 93 10 425 Provision (benefit) for income taxes 15 17 (50 ) 4 (7 ) (a) (21 ) Net income (loss) $ 56 $ 52 $ (179 ) $ 30 $ (24 ) $ (65 ) Net credit-related charge-offs $ 3 $ 11 $ 70 $ — $ — $ 84 Selected average balances: Assets $ 12,899 $ 18,377 $ 11,154 $ 9,766 $ 21,069 $ 73,265 Loans 12,191 18,027 10,566 8,820 — 49,604 Deposits 20,748 17,466 9,204 8,032 1,318 56,768 Statistical data: Return on average assets (b) 1.05 % 1.12 % (6.45 )% 1.24 % n/m (0.35 )% Efficiency ratio (c) 58.91 44.99 58.25 53.76 n/m 56.57 Three Months Ended March 31, 2019 Earnings summary: Net interest income $ 187 $ 205 $ 122 $ 92 $ — $ 606 Provision for credit losses 5 (1 ) (11 ) (8 ) 2 (13 ) Noninterest income 72 40 32 87 7 238 Noninterest expenses 139 100 84 92 18 433 Provision (benefit) for income taxes 26 37 19 19 (16 ) (a) 85 Net income $ 89 $ 109 $ 62 $ 76 $ 3 $ 339 Net credit-related charge-offs (recoveries) $ 4 $ (3 ) $ 13 $ (3 ) $ — $ 11 Selected average balances: Assets $ 13,075 $ 18,934 $ 10,911 $ 8,975 $ 17,876 $ 69,771 Loans 12,557 18,652 10,262 8,206 — 49,677 Deposits 19,893 16,238 8,697 7,906 1,262 53,996 Statistical data: Return on average assets (b) 1.76 % 2.33 % 2.31 % 3.41 % n/m 1.97 % Efficiency ratio (c) 53.66 40.91 54.62 51.28 n/m 50.81 (a) Included discrete tax benefits of $3 million and $11 million for the three months ended March 31, 2020 and 2019 , respectively. (b) Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (c) Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net (losses) gains from securities and a derivative contract tied to the conversion rate of Visa Class B shares. n/m – not meaningful

Revenue from Contracts with Cus

Revenue from Contracts with Customers	3 Months Ended
	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	REVENUE FROM CONTRACTS WITH CUSTOMERS Revenue from contracts with customers comprises the noninterest income earned by the Corporation in exchange for services provided to customers. The following table presents the composition of revenue from contracts with customers, segregated from other sources of noninterest income, by business segment. Business Bank Retail Bank Wealth Management Finance & Other Total (in millions) Three Months Ended March 31, 2020 Revenue from contracts with customers: Card fees $ 49 $ 9 $ 1 $ — $ 59 Service charges on deposit accounts 32 16 1 — 49 Fiduciary income — — 54 — 54 Commercial loan servicing fees (a) 4 — — — 4 Brokerage fees — — 7 — 7 Other noninterest income (b) 4 3 5 — 12 Total revenue from contracts with customers 89 28 68 — 185 Other sources of noninterest income 38 — 2 12 52 Total noninterest income $ 127 $ 28 $ 70 $ 12 $ 237 Three Months Ended March 31, 2019 Revenue from contracts with customers: Card fees $ 53 $ 9 $ 1 $ — $ 63 Service charges on deposit accounts 33 17 1 — 51 Fiduciary income — — 49 — 49 Commercial loan servicing fees (a) 4 — — — 4 Brokerage fees — — 7 — 7 Other noninterest income (b) 2 3 5 — 10 Total revenue from contracts with customers 92 29 63 — 184 Other sources of noninterest income 44 2 1 7 54 Total noninterest income $ 136 $ 31 $ 64 $ 7 $ 238 (a) Included in commercial lending fees on the Consolidated Statements of Comprehensive Income. (b) Excludes derivative, warrant and other miscellaneous income. Adjustments to revenue during the three-month periods ended March 31, 2020 and 2019 for refunds or credits relating to prior periods were not significant. Revenue from contracts with customers did not generate significant contract assets and liabilities.

Basis of Presentation and Acc_2

Basis of Presentation and Accounting Policies Basis of Presentation and Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Allowance For Credit Losses [Policy Text Block]	Allowance for Credit Losses The allowance for credit losses includes both the allowance for loan losses and the allowance for credit losses on lending-related commitments. The Corporation disaggregates the loan portfolio into segments for purposes of determining the allowance for credit losses. These segments are based on the level at which the Corporation develops, documents and applies a systematic methodology to determine the allowance for credit losses. The Corporation's portfolio segments are business loans and retail loans. Business loans include the commercial, real estate construction, commercial mortgage, lease financing and international loan portfolios. Retail loans consist of residential mortgage and consumer loans, including home equity loans. Effective January 1, 2020, the Corporation adopted the provisions of Accounting Standards Update (ASU) No. 2016-13, "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments," commonly referred to as the current expected credit loss (CECL) model, for all financial assets, except those accounted for at fair value through net income, using the modified retrospective approach. Under Topic 326, current expected credit losses are estimated over the contractual life of the loan portfolio, considering all available relevant information, including historical and current conditions as well as reasonable and supportable forecasts of future events. The previous accounting principle estimated probable, estimable losses inherent in the portfolio. At adoption, the Corporation’s estimate of current expected credit losses in accordance with Topic 326 resulted in a $17 million day-one decrease in the overall allowance for credit losses, from $668 million at December 31, 2019 under the incurred loss model. The Corporation recognized a corresponding $13 million increase to retained earnings and a $4 million reduction to deferred tax assets. A similar adjustment at December 31, 2019 would have caused a 2-basis-point increase in the Common Equity Tier 1 (CET1) capital ratio. Business loans, comprising approximately 91 percent of the Corporation’s total loan portfolio at transition, consist of loans and lending arrangements with generally short contractual maturities. As a result, the allowance for credit losses for business loans decreased $42 million . The allowance for credit losses increased $25 million for retail loans, given their longer contractual maturities. Topic 326 also requires expected credit losses on available-for-sale (AFS) debt securities to be recorded as an allowance for credit losses. For certain types of debt securities, such as U.S. Treasuries and other securities with government guarantees, entities may expect zero credit losses. The zero-loss expectation applies to all the Corporation’s securities and no allowance for credit losses were recorded on its AFS securities portfolio at transition. Allowance for Loan Losses The allowance for loan losses is estimated on a quarterly basis and represents management’s estimates of current expected credit losses in the Corporation’s loan portfolio. Pools of loans with similar risk characteristics are collectively evaluated while loans that no longer share risk characteristics with loan pools are evaluated individually. Collective loss estimates are determined by applying reserve factors, designed to estimate current expected credit losses, to amortized cost balances over the remaining contractual life of the collectively evaluated portfolio. Loans with similar risk characteristics are aggregated into homogeneous pools. Business loans are assigned to pools based primarily on business line and the Corporation’s internal risk rating system. For retail loans, pools are based on loan type, past due status and credit scores. Reserve factors are based on estimated probability of default for each pool, set to a default horizon based on contractual life, and loss given default. Historical estimates are calibrated to economic forecasts over the reasonable and supportable forecast period based on the projected performance of specific economic variables that statistically correlate with each of the probability of default and loss given default pools. The calculation of current expected credit losses is inherently subjective, as it requires management to exercise judgment in determining appropriate factors used to determine the allowance. Some of the most significant factors in the quantitative allowance estimate are assigning internal risk ratings to loans, selecting the economic forecasts used to calibrate the reserve factors and determining the reasonable and supportable forecast period. • Internal Risk Ratings : Standard loss factors are dependent on loan risk ratings for business loans. Risk ratings are assigned at origination, based on inherent credit risk, and may be updated based on new information that becomes available, periodic reviews of credit quality, a change in borrower performance or modifications to lending agreements. • Economic Forecasts: Management selects economic variables it believes to be most relevant based on the composition of the loan portfolio and customer base, including forecasted levels of employment, gross domestic product, corporate bond and treasury spreads, industrial production levels, consumer and commercial real estate price indices as well as housing statistics. Different economic forecast scenarios ranging from more benign to more severe are evaluated each reporting period to forecast losses over the contractual life of the loan portfolio. • Forecast Period : Economic forecasts are applied over the period management believes it can estimate reasonable and supportable forecasts. Forecast periods may be adjusted in response to changes in the economic environment. To estimate losses for contractual periods that extend beyond the forecast horizon, the Corporation reverts to an average historical loss experience. The Corporation typically forecasts economic variables over a two-year horizon, followed by an immediate reversion to an average historical loss experience that generally incorporates a full economic cycle. Management reviews this methodology on at least an annual basis. The allowance for loan losses also includes qualitative adjustments to bring the allowance to the level management believes is appropriate based on factors that have not otherwise been fully accounted for, including adjustments for foresight risk, input imprecision and model imprecision. Foresight risk reflects the inherent imprecision in forecasting economic variables, including determining the depth and duration of economic cycles and their impact to relevant economic variables. The Corporation may make qualitative adjustments based on its evaluation of different forecast scenarios and known recent events impacting relevant economic variables. Input imprecision factors address the risk that certain model inputs may not reflect all available information including (i) risk factors that have not been fully addressed in internal risk ratings, (ii) changes in lending policies and procedures, (iii) changes in the level and quality of experience held by lending management, (iv) imprecision in the risk rating system and (v) limitations in data available for certain loan portfolios. Model imprecision considers known model limitations and model updates not yet fully reflected in the quantitative estimate. The determination of the appropriate qualitative adjustment is based on management's analysis of current and expected economic conditions and their impact to the portfolio, as well as internal credit risk movements and a qualitative assessment of the lending environment, including underwriting standards. Management recognizes the sensitivity of various assumptions made in the quantitative modeling of expected losses and may adjust reserves depending upon the level of uncertainty that currently exists in one or more assumptions. Credit losses for loans that no longer share risk characteristics with the loan pools are estimated on an individual basis. Individual credit loss estimates are typically performed for nonaccrual loans and modified loans classified as troubled debt restructurings and are based on one of several methods, including the estimated fair value of the underlying collateral, observable market value of similar debt or the present value of expected cash flows. The Corporation considers certain loans to be collateral-dependent if the borrower is experiencing financial difficulty and management expects repayment for the loan to be substantially through the operation or sale of the collateral. For collateral-dependent loans, loss estimates are based on the fair value of collateral, less estimated cost to sell (if applicable). Collateral values supporting individually evaluated loans are assessed quarterly and appraisals are typically obtained at least annually. The total allowance for loan losses is sufficient to absorb expected credit losses over the contractual life of the portfolio. Unanticipated events impacting the economy, including political instability or global events affecting the U.S. economy, could cause changes to expectations for current conditions and economic forecasts that result in an unanticipated increase in the allowance. Significant increases in current portfolio exposures or changes in credit characteristics could also increase the amount of the allowance. Such events, or others of similar nature, may result in the need for additional provision for credit losses in order to maintain an allowance that complies with credit risk and accounting policies. Loans deemed uncollectible are charged off and deducted from the allowance. Recoveries on loans previously charged off are added to the allowance. Credit losses are not estimated for accrued interest receivable as interest that is deemed uncollectible is written off through interest income. Allowance for Credit Losses on Lending-Related Commitments The allowance for credit losses on lending-related commitments estimates current expected credit losses on collective pools of letters of credit and unused commitments to extend credit based on standard reserve factors, determined in a manner similar to business loans, multiplied by a probability of draw estimate, based on historical experience and credit risk, applied to commitment amounts. The allowance for credit losses on lending-related commitments is included in accrued expenses and other liabilities on the Consolidated Balance Sheets, with the corresponding charge included in the provision for credit losses on the Consolidated Statements of Comprehensive Income.
Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]	Goodwill Effective January 1, 2020, the Corporation prospectively adopted the provisions of ASU No. 2017-04, “Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment,” (ASU 2017-04), eliminating the second step of goodwill impairment testing, under which the implied fair value of goodwill was determined as if the reporting unit were being acquired in a business combination. Under ASU 2017-04, the Corporation will compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for any amount by which the carrying amount exceeds the reporting unit’s fair value, to the extent that the loss recognized does not exceed the amount of goodwill allocated to that reporting unit. The adoption of ASU 2017-04 did not impact the Corporation’s current financial condition or results of operations. Goodwill, included in accrued income and other assets on the Consolidated Balance Sheets, is initially recorded as the excess of the purchase price over the fair value of net assets acquired in a business combination and is subsequently evaluated at least annually for impairment. Goodwill impairment testing is performed at the reporting unit level, equivalent to a business segment or one level below. The Corporation has three reporting units: the Business Bank, the Retail Bank and Wealth Management. The Corporation performs its annual evaluation of goodwill impairment in the third quarter of each year and on an interim basis if events or changes in circumstances between annual tests suggest additional testing may be warranted to determine if goodwill might be impaired. The Corporation may choose to perform a qualitative assessment to determine whether it is more likely than not that the fair value of any reporting unit is less than its carrying amount, including goodwill. Factors considered in the assessment of the likelihood of impairment include macroeconomic conditions, industry and market considerations, stock performance of the Corporation and its peers, financial performance of the reporting units, and previous results of goodwill impairment tests, amongst other factors. Based on the results of the qualitative analysis, the Corporation determines whether a quantitative test is deemed necessary. The quantitative test compares the estimated fair value of identified reporting units with their carrying amount, including goodwill. If the estimated fair value of the reporting unit is less than the carrying value, an impairment charge would be recorded for the excess, not to exceed the amount of goodwill allocated to the reporting unit.
Internal Use Software, Policy [Policy Text Block]	Software Effective January 1, 2020, the Corporation adopted the provisions of ASU No. 2018-15, “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract," using a prospective approach for implementation costs incurred subsequent to the adoption of the standard. Amortization expense from capitalized implementation costs of hosting arrangements that are service contracts and fees associated with the hosting elements of the arrangements, are included in software expense in the Consolidated Statements of Comprehensive Income, along with other software-related expenses. For the three months ended March 31, 2020 , software expense included $7 million of hosting fees that would have previously been included in outside processing fee expense. Capitalized software, stated at cost less accumulated amortization, includes purchased software, capitalizable application development costs associated with internally developed software and cloud computing arrangements, including capitalizable implementation costs associated with hosting arrangements that are service contracts. Amortization, computed on the straight-line method, is charged to software expense in the Consolidated Statements of Comprehensive Income over the estimated useful life of the software, generally 5 years, or the term of the hosting arrangement for implementation costs related to service contracts. Cloud computing arrangements include software as a service (SaaS), platform as a service (PaaS), infrastructure as a service (IaaS) and other similar hosting arrangements. The Corporation primarily utilizes SaaS and IaaS arrangements. Capitalized implementation costs of hosting arrangements that are service contracts were insignificant for the three months ended March 31, 2020 .
Financing Receivable [Policy Text Block]	Reference Rate Reform In March 2020, the Financial Accounting Standards Board (FASB) issued ASU No. 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting,” (ASU 2020-04), to provide temporary optional guidance to ease the potential accounting burden of reference rate reform. ASU 2020-04 is effective for eligible contract modifications from January 1, 2020 through December 31, 2022. Approximately 86 percent of the Corporation’s loans at March 31, 2020 were tied to LIBOR. The Corporation uses interest rate swaps to convert variable-LIBOR rate loans to fixed rates for approximately 10 percent of the loan portfolio. Additional contracts with exposure to LIBOR include swaps converted fixed-rate long-term debt to variable LIBOR rates. The Corporation adopted the provisions of ASU 2020-04 for loan contract modifications as of January 1, 2020 and for all existing hedging relationships as of that date or entered into in the first quarter of 2020.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Assets And Liabilities Recorded At Fair Value On A Recurring Basis	The following tables present the recorded amount of assets and liabilities measured at fair value on a recurring basis as of March 31, 2020 and December 31, 2019 . (in millions) Total Level 1 Level 2 Level 3 March 31, 2020 Deferred compensation plan assets $ 92 $ 92 $ — $ — Equity securities 40 40 — — Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities 2,864 2,864 — — Residential mortgage-backed securities (a) 10,177 — 10,177 — Total investment securities available-for-sale 13,041 2,864 10,177 — Derivative assets: Interest rate contracts 605 — 562 43 Energy derivative contracts 459 — 459 — Foreign exchange contracts 34 — 34 — Total derivative assets 1,098 — 1,055 43 Total assets at fair value $ 14,271 $ 2,996 $ 11,232 $ 43 Derivative liabilities: Interest rate contracts $ 70 $ — $ 70 $ — Energy derivative contracts 454 — 454 — Foreign exchange contracts 27 — 27 — Total derivative liabilities 551 — 551 — Deferred compensation plan liabilities 92 92 — — Total liabilities at fair value $ 643 $ 92 $ 551 $ — December 31, 2019 Deferred compensation plan assets $ 95 $ 95 $ — $ — Equity securities 54 54 — — Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities 2,792 2,792 — — Residential mortgage-backed securities (a) 9,606 — 9,606 — Total investment securities available-for-sale 12,398 2,792 9,606 — Derivative assets: Interest rate contracts 211 — 189 22 Energy derivative contracts 96 — 96 — Foreign exchange contracts 10 — 10 — Total derivative assets 317 — 295 22 Total assets at fair value $ 12,864 $ 2,941 $ 9,901 $ 22 Derivative liabilities: Interest rate contracts $ 39 $ — $ 39 $ — Energy derivative contracts 92 — 92 — Foreign exchange contracts 10 — 10 — Total derivative liabilities 141 — 141 — Deferred compensation plan liabilities 95 95 — — Total liabilities at fair value $ 236 $ 95 $ 141 $ — (a) Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.
Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis	The following table summarizes the changes in Level 3 assets and liabilities measured at fair value on a recurring basis for the three-month periods ended March 31, 2020 and 2019 . Net Realized/Unrealized Gains (Losses) (Pretax) Recorded in Earnings (a) Balance at Beginning of Period Balance at End of Period Payments, Sales and Redemptions (in millions) Realized Unrealized Three Months Ended March 31, 2020 Derivative assets: Interest rate contracts $ 22 $ — $ 21 $ — $ 43 Three Months Ended March 31, 2019 Derivative assets: Interest rate contracts $ 9 $ — $ 5 $ — $ 14 (a) Realized and unrealized gains and losses due to changes in fair value are recorded in other noninterest income on the Consolidated Statements of Comprehensive Income.
Assets And Liabilities Recorded At Fair Value On A Nonrecurring Basis	The following table presents assets recorded at fair value on a nonrecurring basis at March 31, 2020 and December 31, 2019 . No liabilities were recorded at fair value on a nonrecurring basis at March 31, 2020 and December 31, 2019 . (in millions) Level 3 March 31, 2020 Loans: Commercial $ 89 Lease financing 1 Total assets at fair value $ 90 December 31, 2019 Loans: Commercial $ 70 Total assets at fair value $ 70
Estimated Fair Values Of Financial Instruments Not Recorded At Fair Value In Their Entirety On A Recurring Basis	The carrying amount and estimated fair value of financial instruments not recorded at fair value in their entirety on a recurring basis on the Corporation’s Consolidated Balance Sheets are as follows: Carrying Amount Estimated Fair Value (in millions) Total Level 1 Level 2 Level 3 March 31, 2020 Assets Cash and due from banks $ 848 $ 848 $ 848 $ — $ — Interest-bearing deposits with banks 4,007 4,007 4,007 — — Loans held-for-sale 5 5 — 5 — Total loans, net of allowance for loan losses (a) 52,542 52,108 — — 52,108 Customers’ liability on acceptances outstanding 2 2 2 — — Restricted equity investments 279 279 279 — — Nonmarketable equity securities (b) 5 10 Liabilities Demand deposits (noninterest-bearing) 27,646 27,646 — 27,646 — Interest-bearing deposits 26,762 26,762 — 26,762 — Customer certificates of deposit 2,958 2,959 — 2,959 — Total deposits 57,366 57,367 — 57,367 — Short-term borrowings 2,263 2,263 2,263 — — Acceptances outstanding 2 2 2 — — Medium- and long-term debt 7,434 7,224 — 7,224 — Credit-related financial instruments (84 ) (84 ) — — (84 ) December 31, 2019 Assets Cash and due from banks $ 973 $ 973 $ 973 $ — $ — Interest-bearing deposits with banks 4,845 4,845 4,845 — — Loans held-for-sale 6 6 — 6 — Total loans, net of allowance for loan losses (a) 49,732 49,975 — — 49,975 Customers’ liability on acceptances outstanding 2 2 2 — — Restricted equity investments 248 248 248 — — Nonmarketable equity securities (b) 5 10 Liabilities Demand deposits (noninterest-bearing) 27,382 27,382 — 27,382 — Interest-bearing deposits 26,802 26,802 — 26,802 — Certificates of deposit 2,978 2,968 — 2,968 — Other time deposits 133 133 — 133 — Total deposits 57,295 57,285 — 57,285 — Short-term borrowings 71 71 71 — — Acceptances outstanding 2 2 2 — — Medium- and long-term debt 7,269 7,316 — 7,316 — Credit-related financial instruments (57 ) (57 ) — — (57 ) (a) Included $90 million and $70 million of loans recorded at fair value on a nonrecurring basis at March 31, 2020 and December 31, 2019 , respectively. (b) Certain investments that are measured at fair value using the net asset value have not been classified in the fair value hierarchy. The fair value amounts presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets.

Investment Securities (Tables)

Investment Securities (Tables)	3 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Summary Of Investment Securities	A summary of the Corporation’s investment securities follows: (in millions) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value March 31, 2020 Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities $ 2,746 $ 118 $ — $ 2,864 Residential mortgage-backed securities (a) 9,887 290 — 10,177 Total investment securities available-for-sale $ 12,633 $ 408 $ — $ 13,041 December 31, 2019 Investment securities available-for-sale: U.S. Treasury and other U.S. government agency securities $ 2,745 $ 47 $ — $ 2,792 Residential mortgage-backed securities (a) 9,568 66 28 9,606 Total investment securities available-for-sale $ 12,313 $ 113 $ 28 $ 12,398 (a) Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.
Summary Of Investment Securities In Unrealized Loss Positions	A summary of the Corporation’s investment securities in an unrealized loss position as of March 31, 2020 and December 31, 2019 follows: Temporarily Impaired Less than 12 Months 12 Months or more Total (in millions) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses March 31, 2020 Residential mortgage-backed securities (a) $ 110 $ — $ — $ — $ 110 $ — Total temporarily impaired securities $ 110 $ — $ — $ — $ 110 $ — December 31, 2019 Residential mortgage-backed securities (a) $ 1,494 $ 7 $ 1,906 $ 21 $ 3,400 $ 28 Total temporarily impaired securities $ 1,494 $ 7 $ 1,906 $ 21 $ 3,400 $ 28 (a) Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.
Summary of Net Securities Gains (Losses)	Sales, calls and write-downs of investment securities available-for-sale resulted in the following losses recorded in net securities losses on the Consolidated Statements of Comprehensive Income, computed based on the adjusted cost of the specific security. Three Months Ended March 31, (in millions) 2020 2019 Securities gains $ — $ — Securities losses (1 ) (8 ) Net securities losses $ (1 ) $ (8 )
Contractual Maturity Distribution Of Debt Securities	The following table summarizes the amortized cost and fair values of debt securities by contractual maturity. Securities with multiple maturity dates are classified in the period of final maturity. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. (in millions) March 31, 2020 Amortized Cost Fair Value Contractual maturity Within one year $ 30 $ 31 After one year through five years 2,874 2,999 After five years through ten years 884 907 After ten years 8,845 9,104 Total investment securities $ 12,633 $ 13,041

Credit Quality And Allowance _2

Credit Quality And Allowance For Credit Losses (Tables)	3 Months Ended
	Mar. 31, 2020
Credit Quality And Allowance For Credit Losses [Abstract]
Aging Analysis Of Loans	The following table presents an aging analysis of the amortized cost basis of loans. Loans Past Due and Still Accruing (in millions) 30-59 Days 60-89 Days 90 Days or More Total Nonaccrual Loans Current Loans Total Loans March 31, 2020 Business loans: Commercial $ 224 $ 22 $ 42 $ 288 $ 173 $ 33,788 $ 34,249 Real estate construction: Commercial Real Estate business line (a) 4 1 — 5 — 3,341 3,346 Other business lines (b) — — — — — 410 410 Total real estate construction 4 1 — 5 — 3,751 3,756 Commercial mortgage: Commercial Real Estate business line (a) 1 — 8 9 3 2,167 2,179 Other business lines (b) 59 10 10 79 16 7,424 7,519 Total commercial mortgage 60 10 18 88 19 9,591 9,698 Lease financing — — — — 1 583 584 International 14 — 4 18 — 1,017 1,035 Total business loans 302 33 64 399 193 48,730 49,322 Retail loans: Residential mortgage 37 3 — 40 20 1,761 1,821 Consumer: Home equity 5 1 — 6 22 1,699 1,727 Other consumer 1 — — 1 — 587 588 Total consumer 6 1 — 7 22 2,286 2,315 Total retail loans 43 4 — 47 42 4,047 4,136 Total loans $ 345 $ 37 $ 64 $ 446 $ 235 $ 52,777 $ 53,458 December 31, 2019 Business loans: Commercial $ 27 $ 7 $ 17 $ 51 $ 148 $ 31,274 $ 31,473 Real estate construction: Commercial Real Estate business line (a) 6 — — 6 — 3,038 3,044 Other business lines (b) — 7 — 7 — 404 411 Total real estate construction 6 7 — 13 — 3,442 3,455 Commercial mortgage: Commercial Real Estate business line (a) 9 — — 9 2 2,165 2,176 Other business lines (b) 16 18 9 43 12 7,328 7,383 Total commercial mortgage 25 18 9 52 14 9,493 9,559 Lease financing 1 — — 1 — 587 588 International — 5 — 5 — 1,004 1,009 Total business loans 59 37 26 122 162 45,800 46,084 Retail loans: Residential mortgage 15 2 — 17 20 1,808 1,845 Consumer: Home equity 4 5 — 9 17 1,685 1,711 Other consumer 2 3 — 5 — 724 729 Total consumer 6 8 — 14 17 2,409 2,440 Total retail loans 21 10 — 31 37 4,217 4,285 Total loans $ 80 $ 47 $ 26 $ 153 $ 199 $ 50,017 $ 50,369 (a) Primarily loans to real estate developers. (b) Primarily loans secured by owner-occupied real estate.
Loans By Credit Quality Indicator and Vintage Year	The following table presents loans by credit quality indicator and vintage year. Credit quality indicator is based on internal risk ratings assigned to each business loan at the time of approval and subjected to subsequent reviews, generally at least annually, and to pools of retail loans with similar risk characteristics. Vintage year is the year of origination or major modification. March 31, 2020 December 31, 2019 Vintage Year (in millions) 2020 2019 2018 2017 2016 Prior Revolvers Revolvers Converted to Term Total Total Business loans: Commercial: Pass (a) $ 634 $ 2,829 $ 2,069 $ 1,386 $ 636 $ 1,143 $ 23,528 $ 13 $ 32,238 $ 29,785 Special Mention (b) 12 106 72 57 41 47 627 — 962 841 Substandard (c) 3 109 122 24 41 32 544 1 876 699 Nonaccrual (d) 2 11 3 20 10 53 72 2 173 148 Total commercial 651 3,055 2,266 1,487 728 1,275 24,771 16 34,249 31,473 Real estate construction Pass (a) 98 709 1,140 812 527 220 217 — 3,723 3,424 Special Mention (b) — — — — — — 18 — 18 19 Substandard (c) — — 1 14 — — — — 15 12 Total real estate construction 98 709 1,141 826 527 220 235 — 3,756 3,455 Commercial mortgage Pass (a) 472 1,769 1,274 1,323 975 3,114 481 — 9,408 9,262 Special Mention (b) 6 46 18 13 27 50 5 — 165 159 Substandard (c) 2 7 — 11 8 78 — — 106 124 Nonaccrual (d) — — 2 1 3 13 — — 19 14 Total commercial mortgage 480 1,822 1,294 1,348 1,013 3,255 486 — 9,698 9,559 Lease financing Pass (a) 37 147 89 58 18 219 — — 568 579 Special Mention (b) — 6 3 2 2 — — — 13 7 Substandard (c) — 1 — 1 — — — — 2 2 Nonaccrual (d) 1 — — — — — — — 1 — Total lease financing 38 154 92 61 20 219 — — 584 588 International Pass (a) 228 185 161 34 1 74 306 — 989 972 Special Mention (b) — — 4 4 4 2 26 — 40 29 Substandard (c) — — 1 — — — 5 — 6 8 Total international 228 185 166 38 5 76 337 — 1,035 1,009 Total business loans 1,495 5,925 4,959 3,760 2,293 5,045 25,829 16 49,322 46,084 Table continues on the following page. March 31, 2020 December 31, 2019 Vintage Year (in millions) 2020 2019 2018 2017 2016 Prior Revolvers Revolvers Converted to Term Total Total Retail loans: Residential mortgage Pass (a) 136 260 170 340 285 606 — — 1,797 1,823 Special Mention (b) — — 4 — — — — — 4 2 Nonaccrual (d) — — 1 1 2 16 — — 20 20 Total residential mortgage 136 260 175 341 287 622 — — 1,821 1,845 Consumer: Home equity Pass (a) — — — — — 21 1,586 90 1,697 1,682 Special Mention (b) — — — — — — 1 — 1 1 Substandard (c) — — — — — — 4 3 7 11 Nonaccrual (d) — — — — — 1 15 6 22 17 Total home equity — — — — — 22 1,606 99 1,727 1,711 Other consumer Pass (a) 6 89 28 10 11 64 373 — 581 722 Special Mention (b) — — 1 — — — 6 — 7 6 Substandard (c) — — — — — — — — — 1 Total other consumer 6 89 29 10 11 64 379 — 588 729 Total consumer 6 89 29 10 11 86 1,985 99 2,315 2,440 Total retail loans 142 349 204 351 298 708 1,985 99 4,136 4,285 Total loans $ 1,637 $ 6,274 $ 5,163 $ 4,111 $ 2,591 $ 5,753 $ 27,814 $ 115 $ 53,458 $ 50,369 (a) Includes all loans not included in the categories of special mention, substandard or nonaccrual. (b) Special mention loans are accruing loans that have potential credit weaknesses that deserve management’s close attention, such as loans to borrowers who may be experiencing financial difficulties that may result in deterioration of repayment prospects from the borrower at some future date. This category is generally consistent with the "special mention" category as defined by regulatory authorities. (c) Substandard loans are accruing loans that have a well-defined weakness, or weaknesses, such as loans to borrowers who may be experiencing losses from operations or inadequate liquidity of a degree and duration that jeopardizes the orderly repayment of the loan. Substandard loans also are distinguished by the distinct possibility of loss in the future if these weaknesses are not corrected. This category is generally consistent with the "substandard" category as defined by regulatory authorities. (d) Nonaccrual loans are loans for which the accrual of interest has been discontinued. For further information regarding nonaccrual loans, refer to the Nonperforming Assets subheading in Note 1 - Basis of Presentation and Accounting Policies - on page F-51 in the Corporation's 2019 Annual Report. A significant majority of nonaccrual loans are generally consistent with the "substandard" category and the remainder are generally consistent with the "doubtful" category as defined by regulatory authorities.
Changes In The Allowance For Loan Losses	The following table details the changes in the allowance for loan losses. 2020 2019 (in millions) Business Loans Retail Loans Total Business Loans Retail Loans Total Three Months Ended March 31 Balance at beginning of period $ 601 $ 36 $ 637 $ 627 $ 44 $ 671 Cumulative effect of change in accounting principle (42 ) 25 (17 ) — — — Loan charge-offs (87 ) (2 ) (89 ) (19 ) (1 ) (20 ) Recoveries on loans previously charged-off 5 — 5 8 1 9 Net loan charge-offs (82 ) (2 ) (84 ) (11 ) — (11 ) Provision for loan losses 384 (4 ) 380 (8 ) (5 ) (13 ) Balance at end of period $ 861 $ 55 $ 916 $ 608 $ 39 $ 647 As a percentage of total loans 1.75 % 1.35 % 1.71 % 1.33 % 0.88 % 1.29 %
Changes In the Allowance For Credit Losses On Lending-Related Commitments	Changes in the allowance for credit losses on lending-related commitments, included in accrued expenses and other liabilities on the Consolidated Balance Sheets, are summarized in the following table. Three Months Ended March 31, (in millions) 2020 2019 Balance at beginning of period $ 31 $ 30 Provision for credit losses on lending-related commitments 31 — Balance at end of period $ 62 $ 30
Nonaccrual Loans	The following table presents additional information regarding nonaccrual loans. No interest income was recognized on nonaccrual loans for the three months ended March 31, 2020 and 2019 , respectively. (in millions) Nonaccrual Loans with No Related Allowance Nonaccrual Loans with Related Allowance Total Nonaccrual Loans March 31, 2020 Business loans: Commercial $ 25 $ 148 $ 173 Commercial mortgage: Commercial Real Estate business line (a) 2 1 3 Other business lines (b) 3 13 16 Total commercial mortgage 5 14 19 Lease financing — 1 1 Total business loans 30 163 193 Retail loans: Residential mortgage 20 — 20 Consumer: Home equity 22 — 22 Total retail loans 42 — 42 Total nonaccrual loans $ 72 $ 163 $ 235 December 31, 2019 Business loans: Commercial $ 29 $ 119 $ 148 Commercial mortgage: Commercial Real Estate business line (a) 2 — 2 Other business lines (b) 1 11 12 Total commercial mortgage 3 11 14 Total business loans 32 130 162 Retail loans: Residential mortgage 20 — 20 Consumer: Home equity 17 — 17 Total retail loans 37 — 37 Total nonaccrual loans $ 69 $ 130 $ 199 (a) Primarily loans to real estate developers. (b) Primarily loans secured by owner-occupied real estate.
Troubled Debt Restructurings By Type Of Modification	The following table details the amortized cost basis at March 31, 2020 and 2019 of loans considered to be troubled debt restructurings (TDRs) that were restructured during the three-month periods ended March 31, 2020 and 2019 , by type of modification. In cases of loans with more than one type of modification, the loans were categorized based on the most significant modification. Principal Deferrals (a) (in millions) 2020 2019 Three Months Ended March 31, Business loans: Commercial $ 22 $ 12 Commercial mortgage: Other business lines (b) 2 1 Total loans $ 24 $ 13 (a) Primarily represents loan balances where terms were extended by more than an insignificant time period, typically more than 180 days, at or above contractual interest rates. Also includes commercial loans restructured in bankruptcy. (b) Primarily loans secured by owner-occupied real estate.
Troubled Debt Restructuring Subsequent Default	The following table presents information regarding the amortized cost basis at March 31, 2020 and 2019 of loans modified by principal deferral during the twelve-month periods ended March 31, 2020 and 2019 . Principal Deferrals (in millions) 2020 2019 March 31 Business loans: Commercial $ 33 $ 26 Commercial mortgage: Other business lines (a) 2 2 Total business loans 35 28 Retail loans: Consumer: Home equity (b) — 1 Total loans $ 35 $ 29 (a) Primarily loans secured by owner-occupied real estate. (b) Includes bankruptcy loans for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt.

Derivative And Credit-Related_2

Derivative And Credit-Related Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule Of Derivative Instruments	The following table presents the composition of the Corporation’s derivative instruments held or issued for risk management purposes or in connection with customer-initiated and other activities at March 31, 2020 and December 31, 2019 . The table excludes commitments and warrants accounted for as derivatives. March 31, 2020 December 31, 2019 Fair Value Fair Value (in millions) Notional/ Contract Amount (a) Gross Derivative Assets Gross Derivative Liabilities Notional/ Contract Amount (a) Gross Derivative Assets Gross Derivative Liabilities Risk management purposes Derivatives designated as hedging instruments Interest rate contracts: Swaps - fair value - receive fixed/pay floating $ 3,325 $ — $ — $ 3,325 $ — $ — Swaps - cash flow - receive fixed/pay floating 5,550 — — 4,550 — — Derivatives used as economic hedges Foreign exchange contracts: Spot, forwards and swaps 366 3 2 330 — 2 Total risk management purposes 9,241 3 2 8,205 — 2 Customer-initiated and other activities Interest rate contracts: Caps and floors written 681 — — 671 — — Caps and floors purchased 681 — — 671 — — Swaps 19,754 605 70 16,485 211 39 Total interest rate contracts 21,116 605 70 17,827 211 39 Energy contracts: Caps and floors written 439 1 76 477 — 23 Caps and floors purchased 439 76 1 477 23 — Swaps 1,966 382 377 2,135 73 69 Total energy contracts 2,844 459 454 3,089 96 92 Foreign exchange contracts: Spot, forwards, options and swaps 1,531 31 25 1,013 10 8 Total customer-initiated and other activities 25,491 1,095 549 21,929 317 139 Total gross derivatives $ 34,732 $ 1,098 $ 551 $ 30,134 $ 317 $ 141 Amounts offset in the Consolidated Balance Sheets: Netting adjustment - Offsetting derivative assets/liabilities (55 ) (55 ) (63 ) (63 ) Netting adjustment - Cash collateral received/posted (424 ) (23 ) (11 ) (12 ) Net derivatives included in the Consolidated Balance Sheets (b) 619 473 243 66 Amounts not offset in the Consolidated Balance Sheets: Marketable securities pledged under bilateral collateral agreements — (54 ) — (21 ) Net derivatives after deducting amounts not offset in the Consolidated Balance Sheets $ 619 $ 419 $ 243 $ 45 (a) Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Balance Sheets. (b) Net derivative assets are included in accrued income and other assets and net derivative liabilities are included in accrued expenses and other liabilities on the Consolidated Balance Sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and credit risk of the Corporation. The fair value of net derivative assets included credit valuation adjustments for counterparty credit risk of $22 million and $9 million at March 31, 2020 and December 31, 2019 , respectively.
Schedule of the Effects of Fair Value Hedging on the Consolidated Statements of Comprehensive Income	The following table details the effects of fair value hedging on the Consolidated Statements of Comprehensive Income. Interest on Medium- and Long-Term Debt Three Months Ended March 31, (in millions) 2020 2019 Total interest on medium-and long-term debt (a) $ 40 $ 51 Fair value hedging relationships: Interest rate contracts: Hedged items 30 26 Derivatives designated as hedging instruments (6 ) 1 (a) Includes the effects of hedging.
Schedule Of Weighted Average Maturity And Interest Rates On Risk Management Cash Flow Swaps [Text Block]	The following table summarizes the expected weighted average remaining maturity of the notional amount of risk management interest rate swaps, the carrying amount of the related hedged items and the weighted average interest rates associated with amounts expected to be received or paid on interest rate swap agreements as of March 31, 2020 and December 31, 2019 . Cash flow swaps - receive fixed/pay floating rate on variable-rate loans: (dollar amounts in millions) March 31, 2020 December 31, 2019 Derivative Notional Amount $ 5,550 $ 4,550 Weighted Average: Remaining maturity (in years) 3.0 3.0 Receive rate 1.87 % 1.94 % Pay rate (a) 1.58 1.71 (a) Variable rates paid on receive fixed swaps designated as cash flow hedges are based on one-month LIBOR rates in effect at March 31, 2020 and December 31, 2019 .
Schedule Of Weighted Average Maturity And Interest Rates On Risk Management Interest Rate Swaps	Fair value swaps - receive fixed/pay floating rate on medium- and long-term debt: (dollar amounts in millions) March 31, 2020 December 31, 2019 Derivative Notional Amount $ 3,325 $ 3,325 Carrying value of hedged items (a) 3,634 3,469 Weighted Average: Remaining maturity (in years) 4.3 4.6 Receive rate 3.44 % 3.44 % Pay rate (b) 2.32 2.80 (a) Included $ 310 million and $ 146 million of cumulative hedging adjustments at March 31, 2020 and December 31, 2019 , respectively, which included $ 6 million and $ 7 million , respectively, of hedging adjustment on a discontinued hedging relationship. (b) Variable rates paid on receive fixed swaps designated as fair value hedges are based on one- and six-month LIBOR rates in effect at March 31, 2020 and December 31, 2019 .
Schedule Of Net Gains Recognized In Income On Customer-Initiated Derivatives	The net gains recognized in income on customer-initiated derivative instruments, net of the impact of offsetting positions, were as follows . Three Months Ended March 31, (in millions) Location of Gain 2020 2019 Interest rate contracts Other noninterest income $ 8 $ 6 Energy contracts Other noninterest income 1 1 Foreign exchange contracts Foreign exchange income 11 11 Total $ 20 $ 18
Schedule Of Financial Instruments With Off-Balance Sheet Credit Risk	The Corporation’s credit risk associated with these instruments is represented by the contractual amounts indicated in the following table. (in millions) March 31, 2020 December 31, 2019 Unused commitments to extend credit: Commercial and other $ 21,456 $ 23,681 Bankcard, revolving check credit and home equity loan commitments 3,170 3,180 Total unused commitments to extend credit $ 24,626 $ 26,861 Standby letters of credit $ 3,208 $ 3,320 Commercial letters of credit 35 18
Summary Of Criticized Letters Of Credit	The following table presents a summary of criticized standby and commercial letters of credit at March 31, 2020 and December 31, 2019 . The Corporation's criticized list is generally consistent with the Special Mention, Substandard and Doubtful categories defined by regulatory authorities. The Corporation manages credit risk through underwriting, periodically reviewing and approving its credit exposures using Board committee approved credit policies and guidelines. (dollar amounts in millions) March 31, 2020 December 31, 2019 Total criticized standby and commercial letters of credit $ 50 $ 44 As a percentage of total outstanding standby and commercial letters of credit 1.5 % 1.3 %

Variable Interest Entities (V_2

Variable Interest Entities (VIEs) (Tables)	3 Months Ended
	Mar. 31, 2020
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Impact Of VIEs On The Consolidated Statements Of Comprehensive Income	The following table summarizes the impact of these tax credit entities on the Corporation’s Consolidated Statements of Comprehensive Income. Three Months Ended March 31, (in millions) 2020 2019 Other noninterest income: Amortization of other tax credit investments $ — $ 1 Provision for income taxes: Amortization of LIHTC investments 17 15 Low income housing tax credits (16 ) (15 ) Other tax benefits related to tax credit entities (4 ) (3 ) Total provision for income taxes $ (3 ) $ (3 )

Medium- And Long-Term Debt (Tab

Medium- And Long-Term Debt (Tables)	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Schedule Of Medium- And Long-Term Debt	Medium- and long-term debt is summarized as follows: (in millions) March 31, 2020 December 31, 2019 Parent company Subordinated notes: 3.80% subordinated notes due 2026 (a) $ 282 $ 264 Medium- and long-term notes: 3.70% notes due 2023 (a) 917 884 4.00% notes due 2029 (a) 642 587 Total medium- and long-term notes 1,559 1,471 Total parent company 1,841 1,735 Subsidiaries Subordinated notes: 4.00% subordinated notes due 2025 (a) 381 360 7.875% subordinated notes due 2026 (a) 213 202 Total subordinated notes 594 562 Medium- and long-term notes: 2.50% notes due 2020 (a) (b) 675 674 2.50% notes due 2024 (a) 524 498 Total medium- and long-term notes 1,199 1,172 Federal Home Loan Bank (FHLB) advances: Floating-rate based on FHLB auction rate due 2026 2,800 2,800 Floating-rate based on FHLB auction rate due 2028 1,000 1,000 Total FHLB advances 3,800 3,800 Total subsidiaries 5,593 5,534 Total medium- and long-term debt $ 7,434 $ 7,269 (a) The fixed interest rates on these notes have been swapped to a variable rate and designated in a hedging relationship. Accordingly, carrying value has been adjusted to reflect the change in the fair value of the debt as a result of changes in the benchmark rate. (b) Due on June 2, 2020.

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule Of Accumulated Other Comprehensive Loss	The following table presents a reconciliation of the changes in the components of accumulated other comprehensive income (loss) and details the components of other comprehensive income (loss) for the three months ended March 31, 2020 and 2019 , including the amount of income tax expense (benefit) allocated to each component of other comprehensive income (loss). Three Months Ended March 31, (in millions) 2020 2019 Accumulated net unrealized gains (losses) on investment securities: Balance at beginning of period, net of tax $ 65 $ (138 ) Net unrealized holding gains arising during the period 323 109 Less: Provision for income taxes 76 25 Net unrealized holding gains arising during the period, net of tax 247 84 Less: Net realized losses included in net securities losses — (8 ) Less: Benefit for income taxes — (2 ) Reclassification adjustment for net securities losses included in net income, net of tax — (6 ) Change in net unrealized gains on investment securities, net of tax 247 90 Balance at end of period, net of tax $ 312 $ (48 ) Accumulated net gains on cash flow hedges: Balance at beginning of period, net of tax $ 34 $ — Net cash flow hedge gains arising during the period 205 4 Less: Provision for income taxes 48 1 Change in net cash flow hedge gains arising during the period, net of tax 157 3 Less: Net cash flow hedge gains included in interest and fees on loans 3 — Less: Provision for income taxes 1 — Reclassification adjustment for net cash flow hedge gains included in net income, net of tax 2 — Change in net cash flow hedge gains, net of tax 155 3 Balance at end of period, net of tax (a) $ 189 $ 3 Accumulated defined benefit pension and other postretirement plans adjustment: Balance at beginning of period, net of tax $ (334 ) $ (471 ) Amortization of actuarial net loss 16 11 Amortization of prior service credit (7 ) (7 ) Amounts recognized in other noninterest expenses 9 4 Less: Provision for income taxes 2 1 Change in defined benefit pension and other postretirement plans adjustment, net of tax 7 3 Balance at end of period, net of tax $ (327 ) $ (468 ) Total accumulated other comprehensive income (loss) at end of period, net of tax $ 174 $ (513 ) (a) The Corporation expects to reclassify $66 million of net gains, net of tax, from accumulated other comprehensive income to earnings over the next twelve months if interest yield curves and notional amounts remain at March 31, 2020 levels.

Net (Loss) Income Per Common _2

Net (Loss) Income Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Basic And Diluted Net Income Per Common Share	Basic and diluted net (loss) income per common share are presented in the following table. Three Months Ended March 31, (in millions, except per share data) 2020 2019 Basic and diluted Net (loss) income $ (65 ) $ 339 Less: Income allocated to participating securities — 2 Net (loss) income attributable to common shares $ (65 ) $ 337 Basic average common shares 141 158 Basic net (loss) income per common share $ (0.46 ) $ 2.14 Basic average common shares 141 158 Dilutive common stock equivalents: Net effect of the assumed exercise of stock awards — 2 Diluted average common shares 141 160 Diluted net (loss) income per common share $ (0.46 ) $ 2.11 Average shares related to stock awards excluded from the calculation of diluted net (loss) income per share: Exercise price greater than average market price of common shares for the period 1.2 0.4 Anti-dilutive (a) 2.6 — (a) Average exercise price less than average market price of common shares for period; however, anti-dilutive due to net loss during the period.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Components of Net Periodic Benefit Cost	The components of net periodic benefit cost (credit) for the Corporation's qualified pension plan, non-qualified pension plan and postretirement benefit plan are as follows. Qualified Defined Benefit Pension Plan Three Months Ended March 31, (in millions) 2020 2019 Service cost $ 8 $ 8 Other components of net benefit credit: Interest cost 18 20 Expected return on plan assets (43 ) (42 ) Amortization of prior service credit (5 ) (5 ) Amortization of net loss 14 9 Total other components of net benefit credit (16 ) (18 ) Net periodic defined benefit credit $ (8 ) $ (10 ) Non-Qualified Defined Benefit Pension Plan Three Months Ended March 31, (in millions) 2020 2019 Service cost $ 1 $ 1 Other components of net benefit cost: Interest cost 2 2 Amortization of prior service credit (2 ) (2 ) Amortization of net loss 2 2 Total other components of net benefit cost 2 2 Net periodic defined benefit cost $ 3 $ 3 Postretirement Benefit Plan Three Months Ended March 31, (in millions) 2020 2019 Other components of net benefit credit: Interest cost $ — $ 1 Expected return on plan assets — (1 ) Net periodic defined benefit credit $ — $ —

Business Segment Information (T

Business Segment Information (Tables)	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Business Segment Financial Results	Business segment financial results are as follows: Business Retail Wealth Management Finance Other Total (dollar amounts in millions) Three Months Ended March 31, 2020 Earnings summary: Net interest income (expense) $ 380 $ 125 $ 41 $ (44 ) $ 11 $ 513 Provision for credit losses 396 3 12 — — 411 Noninterest income 127 28 70 14 (2 ) 237 Noninterest expenses 194 149 72 — 10 425 (Benefit) provision for income taxes (20 ) — 6 (8 ) 1 (a) (21 ) Net (loss) income $ (63 ) $ 1 $ 21 $ (22 ) $ (2 ) $ (65 ) Net credit-related charge-offs $ 83 $ 1 $ — $ — $ — $ 84 Selected average balances: Assets $ 44,254 $ 2,864 $ 5,078 $ 14,285 $ 6,784 $ 73,265 Loans 42,593 2,075 4,936 — — 49,604 Deposits 30,230 21,195 4,025 1,136 182 56,768 Statistical data: Return on average assets (b) (0.58 )% 0.03 % 1.69 % n/m n/m (0.35 )% Efficiency ratio (c) 38.47 96.03 64.28 n/m n/m 56.57 Three Months Ended March 31, 2019 Earnings summary: Net interest income (expense) $ 412 $ 146 $ 48 $ (15 ) $ 15 $ 606 Provision for credit losses (6 ) (4 ) (5 ) — 2 (13 ) Noninterest income 136 31 64 3 4 238 Noninterest expenses 198 145 72 — 18 433 Provision (benefit) for income taxes 82 8 11 (4 ) (12 ) (a) 85 Net income (loss) $ 274 $ 28 $ 34 $ (8 ) $ 11 $ 339 Net credit-related charge-offs (recoveries) $ 12 $ — $ (1 ) $ — $ — $ 11 Selected average balances: Assets $ 43,909 $ 2,812 $ 5,174 $ 13,585 $ 4,291 $ 69,771 Loans 42,538 2,103 5,036 — — 49,677 Deposits 28,463 20,470 3,801 1,130 132 53,996 Statistical data: Return on average assets (b) 2.53 % 0.54 % 2.67 % n/m n/m 1.97 % Efficiency ratio (c) 36.24 81.34 64.42 n/m n/m 50.81 (a) Included discrete tax benefits of $3 million and $11 million for the three months ended March 31, 2020 and 2019 , respectively. (b) Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (c) Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net (losses) gains from securities and a derivative contract tied to the conversion rate of Visa Class B shares. n/m – not meaningful
Market Segment Financial Results	Market segment financial results are as follows: Michigan California Texas Other Finance Total (dollar amounts in millions) Three Months Ended March 31, 2020 Earnings summary: Net interest income (expense) $ 163 $ 182 $ 115 $ 86 $ (33 ) $ 513 Provision for credit losses 24 51 290 46 — 411 Noninterest income 72 36 30 87 12 237 Noninterest expenses 140 98 84 93 10 425 Provision (benefit) for income taxes 15 17 (50 ) 4 (7 ) (a) (21 ) Net income (loss) $ 56 $ 52 $ (179 ) $ 30 $ (24 ) $ (65 ) Net credit-related charge-offs $ 3 $ 11 $ 70 $ — $ — $ 84 Selected average balances: Assets $ 12,899 $ 18,377 $ 11,154 $ 9,766 $ 21,069 $ 73,265 Loans 12,191 18,027 10,566 8,820 — 49,604 Deposits 20,748 17,466 9,204 8,032 1,318 56,768 Statistical data: Return on average assets (b) 1.05 % 1.12 % (6.45 )% 1.24 % n/m (0.35 )% Efficiency ratio (c) 58.91 44.99 58.25 53.76 n/m 56.57 Three Months Ended March 31, 2019 Earnings summary: Net interest income $ 187 $ 205 $ 122 $ 92 $ — $ 606 Provision for credit losses 5 (1 ) (11 ) (8 ) 2 (13 ) Noninterest income 72 40 32 87 7 238 Noninterest expenses 139 100 84 92 18 433 Provision (benefit) for income taxes 26 37 19 19 (16 ) (a) 85 Net income $ 89 $ 109 $ 62 $ 76 $ 3 $ 339 Net credit-related charge-offs (recoveries) $ 4 $ (3 ) $ 13 $ (3 ) $ — $ 11 Selected average balances: Assets $ 13,075 $ 18,934 $ 10,911 $ 8,975 $ 17,876 $ 69,771 Loans 12,557 18,652 10,262 8,206 — 49,677 Deposits 19,893 16,238 8,697 7,906 1,262 53,996 Statistical data: Return on average assets (b) 1.76 % 2.33 % 2.31 % 3.41 % n/m 1.97 % Efficiency ratio (c) 53.66 40.91 54.62 51.28 n/m 50.81 (a) Included discrete tax benefits of $3 million and $11 million for the three months ended March 31, 2020 and 2019 , respectively. (b) Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity. (c) Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net (losses) gains from securities and a derivative contract tied to the conversion rate of Visa Class B shares. n/m – not meaningful

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	3 Months Ended
	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Composition of Revenue from Contracts with Customers	The following table presents the composition of revenue from contracts with customers, segregated from other sources of noninterest income, by business segment. Business Bank Retail Bank Wealth Management Finance & Other Total (in millions) Three Months Ended March 31, 2020 Revenue from contracts with customers: Card fees $ 49 $ 9 $ 1 $ — $ 59 Service charges on deposit accounts 32 16 1 — 49 Fiduciary income — — 54 — 54 Commercial loan servicing fees (a) 4 — — — 4 Brokerage fees — — 7 — 7 Other noninterest income (b) 4 3 5 — 12 Total revenue from contracts with customers 89 28 68 — 185 Other sources of noninterest income 38 — 2 12 52 Total noninterest income $ 127 $ 28 $ 70 $ 12 $ 237 Three Months Ended March 31, 2019 Revenue from contracts with customers: Card fees $ 53 $ 9 $ 1 $ — $ 63 Service charges on deposit accounts 33 17 1 — 51 Fiduciary income — — 49 — 49 Commercial loan servicing fees (a) 4 — — — 4 Brokerage fees — — 7 — 7 Other noninterest income (b) 2 3 5 — 10 Total revenue from contracts with customers 92 29 63 — 184 Other sources of noninterest income 44 2 1 7 54 Total noninterest income $ 136 $ 31 $ 64 $ 7 $ 238 (a) Included in commercial lending fees on the Consolidated Statements of Comprehensive Income. (b) Excludes derivative, warrant and other miscellaneous income.

Basis of Presentation and Acc_3

Basis of Presentation and Accounting Policies Basis of Presentation and Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Jan. 01, 2019
Increase in the CET1 capital ratio			0.02%
LIBOR loans percent of portfolio	86.00%
Overall allowance for credit losses			$ 668
Cumulative effect of change in accounting principle		$ 13		$ (14)
Business loans percent of portfolio			91.00%
Percent of loan portfolio with interest rate swaps to convert variable-LBIOR to fixed rates	10.00%
Accounting Standards Update 2016-13 [Member]
Day-one decrease in the overall allowance for credit losses		(17)		0
Reduction in business loans allowance for credit losses		(42)		0
Increase in retail loans allowance for credit losses		25		0
Reduction to deferred tax asset		4
Accounting Standards Update 2018-15 [Member]
Hosting fees previously including in outside processing fee expense	$ 7
Retained Earnings
Cumulative effect of change in accounting principle		13		$ (14)
Retained Earnings | Accounting Standards Update 2016-13 [Member]
Cumulative effect of change in accounting principle		$ 13

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Recurring
Transfers into or out of Level 3	$ 0	$ 0
Total liabilities at fair value	643		$ 236
Nonrecurring
Total liabilities at fair value	$ 0		$ 0

Fair Value Measurements (Assets

Fair Value Measurements (Assets And Liabilities Recorded At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		$ 13,041	$ 12,398
Derivative assets		1,098	317
Derivative liabilities		551	141
U.S. Treasury and other U.S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		2,864	2,792
Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[1]	10,177	9,606
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		13,041	12,398
Derivative assets		1,098	317
Total assets at fair value		14,271	12,864
Derivative liabilities		551	141
Deferred compensation plan liabilities		92	95
Total liabilities at fair value		643	236
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		2,864	2,792
Derivative assets		0	0
Total assets at fair value		2,996	2,941
Derivative liabilities		0	0
Deferred compensation plan liabilities		92	95
Total liabilities at fair value		92	95
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		10,177	9,606
Derivative assets		1,055	295
Total assets at fair value		11,232	9,901
Derivative liabilities		551	141
Deferred compensation plan liabilities		0	0
Total liabilities at fair value		551	141
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		0	0
Derivative assets		43	22
Total assets at fair value		43	22
Derivative liabilities		0	0
Deferred compensation plan liabilities		0	0
Total liabilities at fair value		0	0
Recurring | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		605	211
Derivative liabilities		70	39
Recurring | Interest rate contracts | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Recurring | Interest rate contracts | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		562	189
Derivative liabilities		70	39
Recurring | Interest rate contracts | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		43	22
Derivative liabilities		0	0
Recurring | Energy derivative contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		459	96
Derivative liabilities		454	92
Recurring | Energy derivative contracts | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Recurring | Energy derivative contracts | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		459	96
Derivative liabilities		454	92
Recurring | Energy derivative contracts | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Recurring | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		34	10
Derivative liabilities		27	10
Recurring | Foreign exchange contracts | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Recurring | Foreign exchange contracts | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		34	10
Derivative liabilities		27	10
Recurring | Foreign exchange contracts | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Derivative liabilities		0	0
Recurring | Deferred compensation plan assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities		92	95
Recurring | Deferred compensation plan assets | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities		92	95
Recurring | Deferred compensation plan assets | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities		0	0
Recurring | Deferred compensation plan assets | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities		0	0
Recurring | Equity and other non-debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other equity securities		40	54
Recurring | Equity and other non-debt securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other equity securities		40	54
Recurring | Equity and other non-debt securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other equity securities		0	0
Recurring | Equity and other non-debt securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other equity securities		0	0
Recurring | U.S. Treasury and other U.S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		2,864	2,792
Recurring | U.S. Treasury and other U.S. government agency securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		2,864	2,792
Recurring | U.S. Treasury and other U.S. government agency securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		0	0
Recurring | U.S. Treasury and other U.S. government agency securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale		0	0
Recurring | Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[1]	10,177	9,606
Recurring | Residential mortgage-backed securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[1]	0	0
Recurring | Residential mortgage-backed securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[1]	10,177	9,606
Recurring | Residential mortgage-backed securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	[1]	$ 0	$ 0
[1]	Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

Fair Value Measurements (Change

Fair Value Measurements (Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - Interest rate contracts - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Balance at beginning of period		$ 22	$ 9
Realized gains (losses) recorded in earnings	[1]	0	0
Unrealized gains (losses) recorded in earnings	[1]	21	5
Payments, sales and redemptions		0	0
Balance at end of period		$ 43	$ 14
[1]	Realized and unrealized gains and losses due to changes in fair value are recorded in other noninterest income on the Consolidated Statements of Comprehensive Income.

Fair Value Measurements (Asse_2

Fair Value Measurements (Assets And Liabilities Recorded At Fair Value On A Nonrecurring Basis) (Details) - Nonrecurring - Level 3 - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	$ 90	$ 70
Finance Leases Portfolio Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	1
Commercial borrower | Domestic loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	$ 89	$ 70

Fair Value Measurements (Estima

Fair Value Measurements (Estimated Fair Values Of Financial Instruments Not Recorded At Fair Value In Their Entirety On A Recurring Basis) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Cash and due from banks		$ 848	$ 973
Interest-bearing deposits with banks		4,007	4,845
Total loans, net of allowance for loan losses		52,542	49,732
Demand deposits (noninterest-bearing)		27,646	27,382
Customer certificates of deposit		2,958	2,978
Other time deposits		0	133
Total deposits		57,366	57,295
Short-term borrowings		2,263	71
Medium- and long-term debt		7,434	7,269
Carrying Amount
Cash and due from banks		848	973
Interest-bearing deposits with banks		4,007	4,845
Loans held-for-sale		5	6
Total loans, net of allowance for loan losses	[1]	52,542	49,732
Customers' liability on acceptances outstanding		2	2
Restricted equity investments		279	248
Nonmarketable equity securities	[2]	5	5
Demand deposits (noninterest-bearing)		27,646	27,382
Interest-bearing deposits		26,762	26,802
Customer certificates of deposit		2,958	2,978
Other time deposits		0	133
Total deposits		57,366	57,295
Short-term borrowings		2,263	71
Acceptances outstanding		2	2
Medium- and long-term debt		7,434	7,269
Credit-related financial instruments		(84)	(57)
Estimated Fair Value
Cash and due from banks		848	973
Interest-bearing deposits with banks		4,007	4,845
Loans held-for-sale		5	6
Total loans, net of allowance for loan losses	[1]	52,108	49,975
Customers' liability on acceptances outstanding		2	2
Restricted equity investments		279	248
Nonmarketable equity securities	[2]	10	10
Demand deposits (noninterest-bearing)		27,646	27,382
Interest-bearing deposits		26,762	26,802
Customer certificates of deposit		2,959	2,968
Other time deposits		0	133
Total deposits		57,367	57,285
Short-term borrowings		2,263	71
Acceptances outstanding		2	2
Medium- and long-term debt		7,224	7,316
Credit-related financial instruments		(84)	(57)
Level 1 | Estimated Fair Value
Cash and due from banks		848	973
Interest-bearing deposits with banks		4,007	4,845
Loans held-for-sale		0	0
Total loans, net of allowance for loan losses	[1]	0	0
Customers' liability on acceptances outstanding		2	2
Restricted equity investments		279	248
Demand deposits (noninterest-bearing)		0	0
Interest-bearing deposits		0	0
Customer certificates of deposit		0	0
Other time deposits		0	0
Total deposits		0	0
Short-term borrowings		2,263	71
Acceptances outstanding		2	2
Medium- and long-term debt		0	0
Credit-related financial instruments		0	0
Level 2 | Estimated Fair Value
Cash and due from banks		0	0
Interest-bearing deposits with banks		0	0
Loans held-for-sale		5	6
Total loans, net of allowance for loan losses	[1]	0	0
Customers' liability on acceptances outstanding		0	0
Restricted equity investments		0	0
Demand deposits (noninterest-bearing)		27,646	27,382
Interest-bearing deposits		26,762	26,802
Customer certificates of deposit		2,959	2,968
Other time deposits		0	133
Total deposits		57,367	57,285
Short-term borrowings		0	0
Acceptances outstanding		0	0
Medium- and long-term debt		7,224	7,316
Credit-related financial instruments		0	0
Level 3 | Estimated Fair Value
Cash and due from banks		0	0
Interest-bearing deposits with banks		0	0
Loans held-for-sale		0	0
Total loans, net of allowance for loan losses	[1]	52,108	49,975
Customers' liability on acceptances outstanding		0	0
Restricted equity investments		0	0
Demand deposits (noninterest-bearing)		0	0
Interest-bearing deposits		0	0
Customer certificates of deposit		0	0
Other time deposits		0	0
Total deposits		0	0
Short-term borrowings		0	0
Acceptances outstanding		0	0
Medium- and long-term debt		0	0
Credit-related financial instruments		(84)	(57)
Nonrecurring
Total loans, net of allowance for loan losses		$ 90	$ 70
[1]	Included $90 million and $70 million of loans recorded at fair value on a nonrecurring basis at March 31, 2020 and December 31, 2019 , respectively.
[2]	Certain investments that are measured at fair value using the net asset value have not been classified in the fair value hierarchy. The fair value amounts presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets.

Investment Securities (Narrativ

Investment Securities (Narrative) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Investment securities available-for-sale, Amortized Cost		$ 12,633	$ 12,313
Investment securities available-for-sale, Fair Value		13,041	12,398
Carrying value of securities pledged		6,200
Pledged to the FHLB as collateral for potential future borrowings		5,500
FHLB potential future borrowings		5,200
Collateral for potential future borrowings		675
Liabilities secured by pledged collateral		510
U.S. Treasury and other U.S. government agency securities
Investment securities available-for-sale, Amortized Cost		2,746	2,745
Investment securities available-for-sale, Fair Value		2,864	2,792
Residential mortgage-backed securities
Investment securities available-for-sale, Amortized Cost	[1]	9,887	9,568
Investment securities available-for-sale, Fair Value	[1]	10,177	9,606
Debt securities
Investment securities available-for-sale, Amortized Cost		12,633
Investment securities available-for-sale, Fair Value		13,041
Prepayment options | Residential mortgage-backed securities
Investment securities available-for-sale, Amortized Cost		9,900
Investment securities available-for-sale, Fair Value	[1]	10,200
Available-for-sale Securities [Member]
Interest receivable		$ 20	$ 20
[1]	Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

Investment Securities (Summary

Investment Securities (Summary Of Investment Securities) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Investment securities available-for-sale, Amortized Cost		$ 12,633	$ 12,313
Investment securities available-for-sale securities, Gross Unrealized Gains		408	113
Investment securities available-for-sale securities, Gross Unrealized Losses		0	28
Investment securities available-for-sale, Fair Value		13,041	12,398
U.S. Treasury and other U.S. government agency securities
Investment securities available-for-sale, Amortized Cost		2,746	2,745
Investment securities available-for-sale securities, Gross Unrealized Gains		118	47
Investment securities available-for-sale securities, Gross Unrealized Losses		0	0
Investment securities available-for-sale, Fair Value		2,864	2,792
Residential mortgage-backed securities
Investment securities available-for-sale, Amortized Cost	[1]	9,887	9,568
Investment securities available-for-sale securities, Gross Unrealized Gains	[1]	290	66
Investment securities available-for-sale securities, Gross Unrealized Losses	[1]	0	28
Investment securities available-for-sale, Fair Value	[1]	$ 10,177	$ 9,606
[1]	Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

Investment Securities (Summar_2

Investment Securities (Summary Of Investment Securities In Unrealized Loss Positions) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Temporarily Impaired Less than 12 months, Fair Value		$ 110	$ 1,494
Temporarily Impaired Less than 12 Months, Unrealized Losses		0	7
Temporarily Impaired 12 months or more, Fair Value		0	1,906
Temporarily Impaired 12 Months or more, Unrealized Losses		0	21
Temporarily Impaired Total, Fair Value		110	3,400
Temporarily Impaired Total, Unrealized Losses		0	28
Residential mortgage-backed securities
Temporarily Impaired Less than 12 months, Fair Value	[1]	110	1,494
Temporarily Impaired Less than 12 Months, Unrealized Losses	[1]	0	7
Temporarily Impaired 12 months or more, Fair Value	[1]	0	1,906
Temporarily Impaired 12 Months or more, Unrealized Losses	[1]	0	21
Temporarily Impaired Total, Fair Value	[1]	110	3,400
Temporarily Impaired Total, Unrealized Losses	[1]	$ 0	$ 28
[1]	Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

Investment Securities Investmen

Investment Securities Investment Securities (Summary of Net Securities Gains (Losses)) (Details) - Debt securities - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Investments, Debt, and Equity Securities [Abstract]
Securities gains	$ 0	$ 0
Securities losses	(1)	(8)
Net securities losses	$ (1)	$ (8)

Investment Securities (Contract

Investment Securities (Contractual Maturity Distribution Of Debt Securities) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Investment securities available-for-sale, Amortized Cost	$ 12,633	$ 12,313
Investment securities available-for-sale, Fair Value	13,041	$ 12,398
Debt securities
Available-for-sale, Within one year, Amortized Cost	30
Available-for-sale, After one year through five years, Amortized Cost	2,874
Available-for-sale, After five years through ten years, Amortized Cost	884
Available-for-sale, After ten years, Amortized Cost	8,845
Investment securities available-for-sale, Amortized Cost	12,633
Available-for-sale, Within one year, Fair Value	31
Available-for-sale, After one year through five years, Fair Value	2,999
Available-for-sale, After five years through ten years, Fair Value	907
Available-for-sale, After ten years, Fair Value	9,104
Investment securities available-for-sale, Fair Value	$ 13,041

Credit Quality And Allowance _3

Credit Quality And Allowance For Credit Losses (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Financing Receivable, Nonaccrual, Interest Income	$ 0	$ 0
Retail loans secured by residential real estate in process of foreclosure	0		$ 0
Commitments to lend additional funds to TDR borrowers	3		3
Foreclosed properties	$ 11		11
Principal Deferrals
Minimum period loan terms were extended	90 days	90 days
Balance	$ 35	$ 29
Subsequent default during period	$ 10	$ 0
Interest Rate Reductions
Minimum period loan terms were extended	90 days	90 days
Balance	$ 1	$ 4
Subsequent default during period	0	$ 0
Financing Receivable Portfolio Segment [Domain]
Interest receivable	$ 161		$ 172

Credit Quality And Allowance _4

Credit Quality And Allowance For Credit Losses (Aging Analysis Of Loans) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		$ 446	$ 153
Nonaccrual loans		235	199
Current loans		52,777	50,017
Total loans		53,458	50,369
30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		345	80
60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		37	47
90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		64	26
Business loans | Commercial borrower
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		399	122
Nonaccrual loans		193	162
Current loans		48,730	45,800
Total loans		49,322	46,084
Business loans | Commercial borrower | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		302	59
Business loans | Commercial borrower | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		33	37
Business loans | Commercial borrower | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		64	26
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		288	51
Nonaccrual loans		173	148
Current loans		33,788	31,274
Total loans		34,249	31,473
Business loans | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		224	27
Business loans | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		22	7
Business loans | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		42	17
Business loans | Commercial borrower | International loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		18	5
Nonaccrual loans		0	0
Current loans		1,017	1,004
Total loans		1,035	1,009
Business loans | Commercial borrower | International loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		14	0
Business loans | Commercial borrower | International loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	5
Business loans | Commercial borrower | International loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		4	0
Business loans | Real estate construction | Commercial borrower | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		5	13
Nonaccrual loans		0	0
Current loans		3,751	3,442
Total loans		3,756	3,455
Business loans | Real estate construction | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		4	6
Business loans | Real estate construction | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		1	7
Business loans | Real estate construction | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	5	6
Nonaccrual loans	[1]	0	0
Current loans	[1]	3,341	3,038
Total loans	[1]	3,346	3,044
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	4	6
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	1	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	0	7
Nonaccrual loans	[2]	0	0
Current loans	[2]	410	404
Total loans	[2]	410	411
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	0	7
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	0	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		88	52
Nonaccrual loans		19	14	[2]
Current loans		9,591	9,493
Total loans		9,698	9,559
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		60	25
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		10	18
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		18	9
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	9	9
Nonaccrual loans	[1]	3	2
Current loans	[1]	2,167	2,165
Total loans	[1]	2,179	2,176
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	1	9
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	0	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	8	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	79	43
Nonaccrual loans	[2]	16	12
Current loans	[2]	7,424	7,328
Total loans	[2]	7,519	7,383
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	59	16
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	10	18
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	10	9
Business loans | Lease financing | Commercial borrower | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	1
Nonaccrual loans		1	0
Current loans		583	587
Total loans		584	588
Business loans | Lease financing | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	1
Business loans | Lease financing | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Lease financing | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		47	31
Nonaccrual loans		42	37
Current loans		4,047	4,217
Total loans		4,136	4,285
Retail loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		43	21
Retail loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		4	10
Retail loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans | Consumer borrower
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		7	14
Nonaccrual loans		22	17
Current loans		2,286	2,409
Total loans		2,315	2,440
Retail loans | Consumer borrower | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		6	6
Retail loans | Consumer borrower | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		1	8
Retail loans | Consumer borrower | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans | Residential mortgage
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		40	17
Nonaccrual loans		20	20
Current loans		1,761	1,808
Total loans		1,821	1,845
Retail loans | Residential mortgage | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		37	15
Retail loans | Residential mortgage | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		3	2
Retail loans | Residential mortgage | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans | Home equity | Consumer borrower
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		6	9
Nonaccrual loans		22	17
Current loans		1,699	1,685
Total loans		1,727	1,711
Retail loans | Home equity | Consumer borrower | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		5	4
Retail loans | Home equity | Consumer borrower | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		1	5
Retail loans | Home equity | Consumer borrower | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans | Other consumer | Consumer borrower
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		1	5
Nonaccrual loans		0	0
Current loans		587	724
Total loans		588	729
Retail loans | Other consumer | Consumer borrower | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		1	2
Retail loans | Other consumer | Consumer borrower | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	3
Retail loans | Other consumer | Consumer borrower | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		$ 0	$ 0
[1]	Primarily loans to real estate developers.
[2]	Primarily loans secured by owner-occupied real estate.

Credit Quality And Allowance _5

Credit Quality And Allowance For Credit Losses (Loans By Credit Quality Indicator and Vintage Year) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		$ 53,458	$ 50,369
Financing Receivable, Originated in Current Fiscal Year		1,637
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		6,274
Financing Receivable, Originated Two Years before Latest Fiscal Year		5,163
Financing Receivable, Originated Three Years before Latest Fiscal Year		4,111
Financing Receivable, Originated Four Years before Latest Fiscal Year		2,591
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		5,753
Financing Receivable, Revolving		27,814
Financing Receivable, Revolving Converted to Term		115
Business loans | Commercial borrower
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		49,322	46,084
Financing Receivable, Originated in Current Fiscal Year		1,495
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		5,925
Financing Receivable, Originated Two Years before Latest Fiscal Year		4,959
Financing Receivable, Originated Three Years before Latest Fiscal Year		3,760
Financing Receivable, Originated Four Years before Latest Fiscal Year		2,293
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		5,045
Financing Receivable, Revolving		25,829
Financing Receivable, Revolving Converted to Term		16
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		34,249	31,473
Financing Receivable, Originated in Current Fiscal Year		651
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		3,055
Financing Receivable, Originated Two Years before Latest Fiscal Year		2,266
Financing Receivable, Originated Three Years before Latest Fiscal Year		1,487
Financing Receivable, Originated Four Years before Latest Fiscal Year		728
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		1,275
Financing Receivable, Revolving		24,771
Financing Receivable, Revolving Converted to Term		16
Business loans | Commercial borrower | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	32,238	29,785
Financing Receivable, Originated in Current Fiscal Year	[1]	634
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	2,829
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	2,069
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	1,386
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	636
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	1,143
Financing Receivable, Revolving	[1]	23,528
Financing Receivable, Revolving Converted to Term	[1]	13
Business loans | Commercial borrower | Domestic loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	962	841
Financing Receivable, Originated in Current Fiscal Year	[2]	12
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[2]	106
Financing Receivable, Originated Two Years before Latest Fiscal Year	[2]	72
Financing Receivable, Originated Three Years before Latest Fiscal Year	[2]	57
Financing Receivable, Originated Four Years before Latest Fiscal Year	[2]	41
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[2]	47
Financing Receivable, Revolving	[2]	627
Financing Receivable, Revolving Converted to Term	[2]	0
Business loans | Commercial borrower | Domestic loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	876	699
Financing Receivable, Originated in Current Fiscal Year	[3]	3
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	109
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	122
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	24
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	41
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	32
Financing Receivable, Revolving	[3]	544
Financing Receivable, Revolving Converted to Term	[3]	1
Business loans | Commercial borrower | Domestic loans | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	173	148
Financing Receivable, Originated in Current Fiscal Year	[4]	2
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[4]	11
Financing Receivable, Originated Two Years before Latest Fiscal Year	[4]	3
Financing Receivable, Originated Three Years before Latest Fiscal Year	[4]	20
Financing Receivable, Originated Four Years before Latest Fiscal Year	[4]	10
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[4]	53
Financing Receivable, Revolving	[3]	72
Financing Receivable, Revolving Converted to Term	[4]	2
Business loans | Commercial borrower | International loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		1,035	1,009
Financing Receivable, Originated in Current Fiscal Year		228
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		185
Financing Receivable, Originated Two Years before Latest Fiscal Year		166
Financing Receivable, Originated Three Years before Latest Fiscal Year		38
Financing Receivable, Originated Four Years before Latest Fiscal Year		5
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		76
Financing Receivable, Revolving		337
Financing Receivable, Revolving Converted to Term		0
Business loans | Commercial borrower | International loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	989	972
Financing Receivable, Originated in Current Fiscal Year	[1]	228
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	185
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	161
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	34
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	1
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	74
Financing Receivable, Revolving	[1]	306
Financing Receivable, Revolving Converted to Term	[1]	0
Business loans | Commercial borrower | International loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	40	29
Financing Receivable, Originated in Current Fiscal Year	[2]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[2]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[2]	4
Financing Receivable, Originated Three Years before Latest Fiscal Year	[2]	4
Financing Receivable, Originated Four Years before Latest Fiscal Year	[2]	4
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[2]	2
Financing Receivable, Revolving	[2]	26
Financing Receivable, Revolving Converted to Term	[2]	0
Business loans | Commercial borrower | International loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	6	8
Financing Receivable, Originated in Current Fiscal Year	[3]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	1
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	0
Financing Receivable, Revolving	[3]	5
Financing Receivable, Revolving Converted to Term	[3]	0
Business loans | Real estate construction | Commercial borrower | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		3,756	3,455
Financing Receivable, Originated in Current Fiscal Year		98
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		709
Financing Receivable, Originated Two Years before Latest Fiscal Year		1,141
Financing Receivable, Originated Three Years before Latest Fiscal Year		826
Financing Receivable, Originated Four Years before Latest Fiscal Year		527
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		220
Financing Receivable, Revolving		235
Financing Receivable, Revolving Converted to Term		0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	3,723	3,424
Financing Receivable, Originated in Current Fiscal Year	[1]	98
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	709
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	1,140
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	812
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	527
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	220
Financing Receivable, Revolving	[1]	217
Financing Receivable, Revolving Converted to Term	[1]	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	18	19
Financing Receivable, Originated in Current Fiscal Year	[2]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[2]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[2]	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	[2]	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[2]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[2]	0
Financing Receivable, Revolving	[2]	18
Financing Receivable, Revolving Converted to Term	[2]	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	15	12
Financing Receivable, Originated in Current Fiscal Year	[3]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	1
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	14
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	0
Financing Receivable, Revolving	[3]	0
Financing Receivable, Revolving Converted to Term	[3]	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		9,698	9,559
Financing Receivable, Originated in Current Fiscal Year		480
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		1,822
Financing Receivable, Originated Two Years before Latest Fiscal Year		1,294
Financing Receivable, Originated Three Years before Latest Fiscal Year		1,348
Financing Receivable, Originated Four Years before Latest Fiscal Year		1,013
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		3,255
Financing Receivable, Revolving		486
Financing Receivable, Revolving Converted to Term		0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	9,408	9,262
Financing Receivable, Originated in Current Fiscal Year	[1]	472
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	1,769
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	1,274
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	1,323
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	975
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	3,114
Financing Receivable, Revolving	[1]	481
Financing Receivable, Revolving Converted to Term	[1]	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	165	159
Financing Receivable, Originated in Current Fiscal Year	[2]	6
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[2]	46
Financing Receivable, Originated Two Years before Latest Fiscal Year	[2]	18
Financing Receivable, Originated Three Years before Latest Fiscal Year	[2]	13
Financing Receivable, Originated Four Years before Latest Fiscal Year	[2]	27
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[2]	50
Financing Receivable, Revolving	[2]	5
Financing Receivable, Revolving Converted to Term	[2]	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	106	124
Financing Receivable, Originated in Current Fiscal Year	[3]	2
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	7
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	11
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	8
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	78
Financing Receivable, Revolving	[3]	0
Financing Receivable, Revolving Converted to Term	[3]	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	19	14
Financing Receivable, Originated in Current Fiscal Year	[4]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[4]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[4]	2
Financing Receivable, Originated Three Years before Latest Fiscal Year	[4]	1
Financing Receivable, Originated Four Years before Latest Fiscal Year	[4]	3
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[4]	13
Financing Receivable, Revolving	[4]	0
Financing Receivable, Revolving Converted to Term	[4]	0
Business loans | Lease financing | Commercial borrower | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		584	588
Financing Receivable, Originated in Current Fiscal Year		38
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		154
Financing Receivable, Originated Two Years before Latest Fiscal Year		92
Financing Receivable, Originated Three Years before Latest Fiscal Year		61
Financing Receivable, Originated Four Years before Latest Fiscal Year		20
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		219
Financing Receivable, Revolving		0
Financing Receivable, Revolving Converted to Term		0
Business loans | Lease financing | Commercial borrower | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	568	579
Financing Receivable, Originated in Current Fiscal Year	[1]	37
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	147
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	89
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	58
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	18
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	219
Financing Receivable, Revolving	[1]	0
Financing Receivable, Revolving Converted to Term	[1]	0
Business loans | Lease financing | Commercial borrower | Domestic loans | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	13	7
Financing Receivable, Originated in Current Fiscal Year	[2]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[2]	6
Financing Receivable, Originated Two Years before Latest Fiscal Year	[2]	3
Financing Receivable, Originated Three Years before Latest Fiscal Year	[2]	2
Financing Receivable, Originated Four Years before Latest Fiscal Year	[2]	2
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[2]	0
Financing Receivable, Revolving	[2]	0
Financing Receivable, Revolving Converted to Term	[2]	0
Business loans | Lease financing | Commercial borrower | Domestic loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	2	2
Financing Receivable, Originated in Current Fiscal Year	[3]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	1
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	1
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	0
Financing Receivable, Revolving	[3]	0
Financing Receivable, Revolving Converted to Term	[3]	0
Business loans | Lease financing | Commercial borrower | Domestic loans | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	1	0
Financing Receivable, Originated in Current Fiscal Year	[4]	1
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[4]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[4]	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	[4]	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[4]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[4]	0
Financing Receivable, Revolving	[4]	0
Financing Receivable, Revolving Converted to Term	[4]	0
Retail loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		4,136	4,285
Financing Receivable, Originated in Current Fiscal Year		142
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		349
Financing Receivable, Originated Two Years before Latest Fiscal Year		204
Financing Receivable, Originated Three Years before Latest Fiscal Year		351
Financing Receivable, Originated Four Years before Latest Fiscal Year		298
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		708
Financing Receivable, Revolving		1,985
Financing Receivable, Revolving Converted to Term		99
Retail loans | Consumer borrower
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		2,315	2,440
Financing Receivable, Originated in Current Fiscal Year		6
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		89
Financing Receivable, Originated Two Years before Latest Fiscal Year		29
Financing Receivable, Originated Three Years before Latest Fiscal Year		10
Financing Receivable, Originated Four Years before Latest Fiscal Year		11
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		86
Financing Receivable, Revolving		1,985
Financing Receivable, Revolving Converted to Term		99
Retail loans | Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		1,821	1,845
Financing Receivable, Originated in Current Fiscal Year		136
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		260
Financing Receivable, Originated Two Years before Latest Fiscal Year		175
Financing Receivable, Originated Three Years before Latest Fiscal Year		341
Financing Receivable, Originated Four Years before Latest Fiscal Year		287
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		622
Financing Receivable, Revolving		0
Financing Receivable, Revolving Converted to Term		0
Retail loans | Residential mortgage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	1,797	1,823
Financing Receivable, Originated in Current Fiscal Year	[1]	136
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	260
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	170
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	340
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	285
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	606
Financing Receivable, Revolving	[1]	0
Financing Receivable, Revolving Converted to Term	[1]	0
Retail loans | Residential mortgage | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	4	2
Financing Receivable, Originated in Current Fiscal Year	[2]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[2]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[2]	4
Financing Receivable, Originated Three Years before Latest Fiscal Year	[2]	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[2]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[2]	0
Financing Receivable, Revolving	[2]	0
Financing Receivable, Revolving Converted to Term	[2]	0
Retail loans | Residential mortgage | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	20	20
Financing Receivable, Originated in Current Fiscal Year	[4]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[4]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[4]	1
Financing Receivable, Originated Three Years before Latest Fiscal Year	[4]	1
Financing Receivable, Originated Four Years before Latest Fiscal Year	[4]	2
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[4]	16
Financing Receivable, Revolving	[4]	0
Financing Receivable, Revolving Converted to Term	[4]	0
Retail loans | Home equity | Consumer borrower
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		1,727	1,711
Financing Receivable, Originated in Current Fiscal Year		0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		0
Financing Receivable, Originated Two Years before Latest Fiscal Year		0
Financing Receivable, Originated Three Years before Latest Fiscal Year		0
Financing Receivable, Originated Four Years before Latest Fiscal Year		0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		22
Financing Receivable, Revolving		1,606
Financing Receivable, Revolving Converted to Term		99
Retail loans | Home equity | Consumer borrower | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	1,697	1,682
Financing Receivable, Originated in Current Fiscal Year	[1]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	21
Financing Receivable, Revolving	[1]	1,586
Financing Receivable, Revolving Converted to Term	[1]	90
Retail loans | Home equity | Consumer borrower | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	1	1
Financing Receivable, Originated in Current Fiscal Year	[2]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[2]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[2]	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	[2]	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[2]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[2]	0
Financing Receivable, Revolving	[2]	1
Financing Receivable, Revolving Converted to Term	[2]	0
Retail loans | Home equity | Consumer borrower | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	7	11
Financing Receivable, Originated in Current Fiscal Year	[3]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	0
Financing Receivable, Revolving	[3]	4
Financing Receivable, Revolving Converted to Term	[3]	3
Retail loans | Home equity | Consumer borrower | Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[4]	22	17
Financing Receivable, Originated in Current Fiscal Year	[4]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[4]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[4]	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	[4]	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[4]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[4]	1
Financing Receivable, Revolving	[4]	15
Financing Receivable, Revolving Converted to Term	[4]	6
Retail loans | Other consumer | Consumer borrower
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		588	729
Financing Receivable, Originated in Current Fiscal Year		6
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		89
Financing Receivable, Originated Two Years before Latest Fiscal Year		29
Financing Receivable, Originated Three Years before Latest Fiscal Year		10
Financing Receivable, Originated Four Years before Latest Fiscal Year		11
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		64
Financing Receivable, Revolving		379
Financing Receivable, Revolving Converted to Term		0
Retail loans | Other consumer | Consumer borrower | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	581	722
Financing Receivable, Originated in Current Fiscal Year	[1]	6
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	89
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	28
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	10
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	11
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	64
Financing Receivable, Revolving	[1]	373
Financing Receivable, Revolving Converted to Term	[1]	0
Retail loans | Other consumer | Consumer borrower | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[2]	7	6
Financing Receivable, Originated in Current Fiscal Year	[2]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[2]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[2]	1
Financing Receivable, Originated Three Years before Latest Fiscal Year	[2]	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[2]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[2]	0
Financing Receivable, Revolving	[2]	6
Financing Receivable, Revolving Converted to Term	[2]	0
Retail loans | Other consumer | Consumer borrower | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	0	$ 1
Financing Receivable, Originated in Current Fiscal Year	[3]	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	0
Financing Receivable, Revolving	[3]	0
Financing Receivable, Revolving Converted to Term	[3]	$ 0
[1]	Includes all loans not included in the categories of special mention, substandard or nonaccrual.
[2]	Special mention loans are accruing loans that have potential credit weaknesses that deserve management’s close attention, such as loans to borrowers who may be experiencing financial difficulties that may result in deterioration of repayment prospects from the borrower at some future date. This category is generally consistent with the "special mention" category as defined by regulatory authorities.
[3]	Substandard loans are accruing loans that have a well-defined weakness, or weaknesses, such as loans to borrowers who may be experiencing losses from operations or inadequate liquidity of a degree and duration that jeopardizes the orderly repayment of the loan. Substandard loans also are distinguished by the distinct possibility of loss in the future if these weaknesses are not corrected. This category is generally consistent with the "substandard" category as defined by regulatory authorities.
[4]	Nonaccrual loans are loans for which the accrual of interest has been discontinued. For further information regarding nonaccrual loans, refer to the Nonperforming Assets subheading in Note 1 - Basis of Presentation and Accounting Policies - on page F-51 in the Corporation's 2019 Annual Report. A significant majority of nonaccrual loans are generally consistent with the "substandard" category and the remainder are generally consistent with the "doubtful" category as defined by regulatory authorities.

Credit Quality And Allowance _6

Credit Quality And Allowance For Credit Losses (Changes In The Allowance For Loan Losses And Related Loan Amounts) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Jan. 01, 2020	Mar. 31, 2019	Jan. 01, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for loan losses	$ 411	$ (13)
Financing Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	637	671
Loan charge-offs	(89)	(20)
Recoveries on loans previously charged-off	5	9
Net loan charge-offs	(84)	(11)
Provision for loan losses	380	(13)
Balance at end of period	916	647
As a percentage of total loans			1.71%		1.29%
Total allowance for loan losses	916	647	$ 916		$ 647
Business loans | Financing Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	601	627
Loan charge-offs	(87)	(19)
Recoveries on loans previously charged-off	5	8
Net loan charge-offs	(82)	(11)
Provision for loan losses	384	(8)
Balance at end of period	861	608
As a percentage of total loans			1.75%		1.33%
Total allowance for loan losses	861	608	$ 861		$ 608
Retail loans | Financing Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	36	44
Loan charge-offs	(2)	(1)
Recoveries on loans previously charged-off	0	1
Net loan charge-offs	(2)	0
Provision for loan losses	(4)	(5)
Balance at end of period	55	39
As a percentage of total loans			1.35%		0.88%
Total allowance for loan losses	$ 55	$ 39	$ 55		$ 39
Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Reduction in business loans allowance for credit losses				$ (42)		$ 0
Increase in retail loans allowance for credit losses				25		0
Day-one decrease in the overall allowance for credit losses				$ (17)		$ 0

Credit Quality And Allowance _7

Credit Quality And Allowance For Credit Losses (Changes In The Allowance For Credit Losses On Lending-Related Commitments) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for credit losses	$ 411	$ (13)
Lending-related commitments
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	31	30
Provision for credit losses	(31)	0
Balance at end of period	$ 62	$ 30

Credit Quality And Allowance _8

Credit Quality And Allowance For Credit Losses (Nonaccrual Loans) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		$ 72	$ 69
Financing Receivable, Nonaccrual		163	130
Nonaccrual loans		235	199
Business loans | Commercial borrower
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		30	32
Financing Receivable, Nonaccrual		163	130
Nonaccrual loans		193	162
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		25	29
Financing Receivable, Nonaccrual		148	119
Nonaccrual loans		173	148
Business loans | Commercial borrower | International loans
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans		0	0
Retail loans
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		42	37
Financing Receivable, Nonaccrual		0	0
Nonaccrual loans		42	37
Retail loans | Consumer borrower
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans		22	17
Commercial mortgage | Business loans | Commercial borrower | Domestic loans
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		5	3
Financing Receivable, Nonaccrual		14	11
Nonaccrual loans		19	14	[1]
Commercial mortgage | Commercial Real Estate business line | Business loans | Commercial borrower | Domestic loans
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance	[2]	2	2
Financing Receivable, Nonaccrual	[2]	1	0
Nonaccrual loans	[2]	3	2
Commercial mortgage | Other business lines | Business loans | Commercial borrower | Domestic loans
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance	[1]	3	1
Financing Receivable, Nonaccrual	[1]	13	11
Nonaccrual loans	[1]	16	12
Residential mortgage | Retail loans
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		20	20
Financing Receivable, Nonaccrual		0	0
Nonaccrual loans		20	20
Home equity | Retail loans | Consumer borrower
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		22	17
Financing Receivable, Nonaccrual		0	0
Nonaccrual loans		22	17
Other consumer | Retail loans | Consumer borrower
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans		0	$ 0
Business Loans | Finance Leases Portfolio Segment [Member] | Commercial borrower | Domestic loans
Financing Receivable, Nonaccrual [Line Items]
Financing Receivable, Nonaccrual, No Allowance		0
Financing Receivable, Nonaccrual		1
Nonaccrual loans		$ 1
[1]	Primarily loans secured by owner-occupied real estate.
[2]	Primarily loans to real estate developers.

Credit Quality And Allowance _9

Credit Quality And Allowance For Credit Losses (Troubled Debt Restructurings By Type Of Modification) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Nonaccrual, Interest Income		$ 0	$ 0
Principal Deferrals
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification	[1]	24	13
Principal Deferrals | Business loans | Commercial borrower | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification	[1]	22	12
Principal Deferrals | Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification	[1],[2]	$ 2	$ 1
[1]	Primarily represents loan balances where terms were extended by more than an insignificant time period, typically more than 180
[2]	Primarily loans secured by owner-occupied real estate.

Credit Quality And Allowance_10

Credit Quality And Allowance For Credit Losses Foreclosed Properties (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Nonaccrual Loans [Abstract]
Foreclosed properties	$ 11	$ 11

Credit Quality And Allowance_11

Credit Quality And Allowance For Credit Losses Credit Quality And Allowance For Credit Losses (Troubled Debt Restructuring Subsequent Default) (Details) - Principal Deferrals - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Financing Receivable, Troubled Debt Restructuring [Line Items]
Balance		$ 35	$ 29
Subsequent default during period		10	0
Business loans | Commercial borrower
Financing Receivable, Troubled Debt Restructuring [Line Items]
Balance		35	28
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Balance		33	26
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Troubled Debt Restructuring [Line Items]
Balance	[1]	2	2
Retail loans | Home equity | Consumer borrower | Domestic loans | Commercial Real Estate business line
Financing Receivable, Troubled Debt Restructuring [Line Items]
Balance	[2]	$ 0	$ 1
[1]	Primarily loans secured by owner-occupied real estate.
[2]	Includes bankruptcy loans for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt.

Derivative And Credit-Related_3

Derivative And Credit-Related Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Cash received as collateral for derivative assets	$ 427
Fair value of securities pledged as collateral for derivative assets	59
Cash posted as collateral for derivative liabilities	26
Aggregate fair value of all derivative instruments with credit-risk contingent features that were in a liability position	0
Net gain on open foreign currency positions	0	$ 0
Allowance for credit losses on lending-related commitments	62		$ 31
Allowance for credit losses on lending-related commitments, amount related to unused commitments to extend credit	$ 51		25
Final year of expiration for outstanding letters of credit	2028
Risk participation agreements covering standby and commercial letters of credit	$ 160		161
Standby and commercial letters of credit	3,200		3,300
Carrying value of standby and commercial letters of credit included in accrued expenses and other liabilities	33		32
Deferred fees on standby and commercial letters of credit included in accrued expenses and other liabilities	23		26
Allowance for credit losses on lending-related commitments, amount related to standby and commercial letters of credit	10		6
Notional amount of derivative credit risk participation agreements	807		786
Maximum estimated exposure to credit risk participation agreements assuming 100% default	$ 50		$ 20
Weighted average remaining maturity of credit risk participation agreements, in years	3 years 4 months 24 days

Derivative And Credit-Related_4

Derivative And Credit-Related Financial Instruments (Schedule Of Derivative Instruments) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	$ 34,732	$ 30,134
Fair Value of Gross Derivative Assets		1,098	317
Fair Value of Gross Derivative Liabilities		551	141
Derivative assets, Netting adjustment - Offsetting derivative liabilities		(55)	(63)
Derivative liabilities, Netting adjustment - Offsetting derivative assets		(55)	(63)
Derivative assets, Netting adjustment - Cash collateral received		(424)	(11)
Derivative liabilities, Netting adjustment, Cash collateral posted		(23)	(12)
Net derivative assets included in the consolidated balance sheets	[2]	619	243
Net derivative liabilities included in the consolidated balance sheets	[2]	473	66
Derivative asset, securities pledged as collateral		0	0
Derivative liability, securities pledged as collateral		(54)	(21)
Net derivative assets after deducting amounts not offset in the consolidated balance sheets		619	243
Net derivative liabilities after deducting amounts not offset in the consolidated balance sheets		419	45
Credit valuation adjustments for counterparty credit risk		22	9
Risk management purposes
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	9,241	8,205
Fair Value of Gross Derivative Assets		3	0
Fair Value of Gross Derivative Liabilities		2	2
Risk management purposes | Derivatives designated as hedging instruments | Swaps - fair value - receive fixed/pay floating | Interest rate swap
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	3,325	4,550
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		0	0
Risk management purposes | Derivatives designated as hedging instruments | Swaps - cash flow - receive fixed/pay floating rate | Interest rate swap
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	5,550	3,325
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		0	0
Risk management purposes | Derivatives used as economic hedges | Foreign exchange spot, forwards and swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	366	330
Fair Value of Gross Derivative Assets		3	0
Fair Value of Gross Derivative Liabilities		2	2
Customer-initiated and other activities
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	25,491	21,929
Fair Value of Gross Derivative Assets		1,095	317
Fair Value of Gross Derivative Liabilities		549	139
Customer-initiated and other activities | Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	21,116	17,827
Fair Value of Gross Derivative Assets		605	211
Fair Value of Gross Derivative Liabilities		70	39
Customer-initiated and other activities | Interest rate caps and floors written
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	681	671
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		0	0
Customer-initiated and other activities | Interest rate caps and floors purchased
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	681	671
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		0	0
Customer-initiated and other activities | Interest rate swap
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	19,754	16,485
Fair Value of Gross Derivative Assets		605	211
Fair Value of Gross Derivative Liabilities		70	39
Customer-initiated and other activities | Energy contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	2,844	3,089
Fair Value of Gross Derivative Assets		459	96
Fair Value of Gross Derivative Liabilities		454	92
Customer-initiated and other activities | Energy caps and floors written
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	439	477
Fair Value of Gross Derivative Assets		1	0
Fair Value of Gross Derivative Liabilities		76	23
Customer-initiated and other activities | Energy caps and floors purchased
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	439	477
Fair Value of Gross Derivative Assets		76	23
Fair Value of Gross Derivative Liabilities		1	0
Customer-initiated and other activities | Energy swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	1,966	2,135
Fair Value of Gross Derivative Assets		382	73
Fair Value of Gross Derivative Liabilities		377	69
Customer-initiated and other activities | Foreign exchange spot, options and swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	1,531	1,013
Fair Value of Gross Derivative Assets		31	10
Fair Value of Gross Derivative Liabilities		$ 25	$ 8
[1]	Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Balance Sheets.
[2]	Net derivative assets are included in accrued income and other assets and net derivative liabilities are included in accrued expenses and other liabilities on the Consolidated Balance Sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and credit risk of the Corporation. The fair value of net derivative assets included credit valuation adjustments for counterparty credit risk of $22 million and $9 million at March 31, 2020 and December 31, 2019 , respectively.

Derivative And Credit-Related_5

Derivative And Credit-Related Financial Instruments Derivative and Credit-Related Financial Instruments (Schedule of the Effects of Fair Value Hedging on the Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Total interest on medium- and long-term debt	[1]	$ 40	$ 51
Swaps - fair value - receive fixed/pay floating | Risk management purposes | Interest rate swap
Interest rate contract: Hedge items interest expense		30	26
Interest rate contracts: Derivatives designated as hedging instruments net interest income		$ (6)	$ 1
[1]	Includes the effects of hedging.

Derivative And Credit-Related_6

Derivative And Credit-Related Financial Instruments (Schedule Of Weighted Average Maturity And Interest Rates On Risk Management Cash Flow Swaps) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Derivative, Notional Amount	[1]	$ 34,732		$ 30,134
Risk management purposes
Derivative, Notional Amount	[1]	9,241		8,205
Variable rate loans | Swaps - cash flow - receive fixed/pay floating rate | Risk management purposes | Cash flow swap
Derivative, Notional Amount		$ 5,550		$ 4,550
Weighted Average Remaining Maturity		3 years	3 years
Derivative, Average Fixed Interest Rate		1.87%		1.94%
Derivative, Average Variable Interest Rate	[2]	1.58%		1.71%
[1]	Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Balance Sheets.
[2]	Variable rates paid on receive fixed swaps designated as cash flow hedges are based on one-month LIBOR rates in effect at March 31, 2020 and December 31, 2019 .

Derivative And Credit-Related_7

Derivative And Credit-Related Financial Instruments Derivative And Credit-Related Financial Instruments (Schedule Of Weighted Average Maturity And Interest Rates On Risk Management Fair Value Swaps) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2020	Dec. 31, 2019
Derivative, Notional Amount	[1]	$ 34,732	$ 30,134
Risk management purposes
Derivative, Notional Amount	[1]	9,241	8,205
Interest rate swap | Fair Value Hedging [Member] | Risk management purposes | Long-term Debt [Member]
Derivative, Notional Amount		3,325	3,325
Carryingvalueofhedgeditem	[2]	$ 3,634	$ 3,469
Weighted Average Remaining Maturity		4 years 3 months 18 days	4 years 7 months 6 days
Derivative, Average Fixed Interest Rate		3.44%	3.44%
Derivative, Average Variable Interest Rate	[3]	2.32%	2.80%
[1]	Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Balance Sheets.
[2]	Included $ 310 million and $ 146 million of cumulative hedging adjustments at March 31, 2020 and December 31, 2019 , respectively, which included $ 6 million and $ 7 million
[3]	Variable rates paid on receive fixed swaps designated as fair value hedges are based on one- and six-month LIBOR rates in effect at March 31, 2020 and December 31, 2019 .

Derivative And Credit-Related_8

Derivative And Credit-Related Financial Instruments (Schedule Of Net Gains Recognized In Income On Customer-Initiated Derivatives) (Details) - Customer-initiated and other activities - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	$ 20	$ 18
Interest rate contracts | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	8	6
Energy contracts | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	1	1
Foreign exchange contracts | Foreign exchange income
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	$ 11	$ 11

Derivative And Credit-Related_9

Derivative And Credit-Related Financial Instruments (Schedule Of Financial Instruments With Off-Balance Sheet Credit Risk) (Details) - Maximum - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss	$ 24,626	$ 26,861
Commercial And Other | Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss	21,456	23,681
Bankcard, Revolving Check Credit And Home Equity Loan Commitments | Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss	3,170	3,180
Standby Letters Of Credit
Loss contingency, estimate of possible loss	3,208	3,320
Commercial Letters Of Credit
Loss contingency, estimate of possible loss	$ 35	$ 18

Derivative And Credit-Relate_10

Derivative And Credit-Related Financial Instruments (Summary Of Internally Classified Watch List Letters Of Credit) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Total criticized standby and commercial letters of credit	$ 50	$ 44
As a percentage of total outstanding standby and commercial letters of credit	1.50%	1.30%

Variable Interest Entities (V_3

Variable Interest Entities (VIEs) (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Variable Interest Entity
Unfunded commitments to fund tax credit entities	$ 167
Amount of financial or other support not contractually required provided by the Corporation to VIEs	0	$ 0
Low Income Housing Tax Credit Entities
Variable Interest Entity
Exposure to loss as a result of involvement with VIEs	453
Other Tax Credit Entities [Member]
Variable Interest Entity
Exposure to loss as a result of involvement with VIEs	$ 0

Variable Interest Entities (V_4

Variable Interest Entities (VIEs) (Impact Of VIEs On The Consolidated Statements Of Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Variable Interest Entity
Other noninterest income	$ 20	$ 25
Provision for income taxes	(21)	85
Variable Interest Entity
Variable Interest Entity
Other noninterest income	0	1
Provision for income taxes	(3)	(3)
Variable Interest Entity | Low income housing tax credits
Variable Interest Entity
Provision for income taxes, amortization of LIHTC investments	17	15
Provision for income taxes, affordable housing tax credits and other tax benefits	(16)	(15)
Variable Interest Entity | Other tax benefits related to tax credit entities
Variable Interest Entity
Provision for income taxes, affordable housing tax credits and other tax benefits	$ (4)	$ (3)

Medium- And Long-Term Debt (Nar

Medium- And Long-Term Debt (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Federal Home Loan Bank, Advances, Weighted Average Interest Rate	0.92%
Potential future borrowings	$ 9,900
Pledged to the FHLB as collateral for potential future borrowings	5,500
Short-term Federal Home Loan Bank Advances	750
Long-term Federal Home Loan Bank Advances	3,800
Unamortized debt issuance cost	11	$ 12
Subsidiaries
Debt Instrument [Line Items]
Real estate-related loans securing FHLB advances	17,600
Long-term Federal Home Loan Bank Advances	$ 3,800	3,800
Floating-rate based on FHLB auction rate due 2026 | Subsidiaries
Debt Instrument [Line Items]
Weighted-average interest rate	0.72%
Long-term Federal Home Loan Bank Advances	$ 2,800	2,800
Floating-rate based on FHLB auction rate due 2028 | Subsidiaries
Debt Instrument [Line Items]
Weighted-average interest rate	1.47%
Long-term Federal Home Loan Bank Advances	$ 1,000	$ 1,000
Debt Instrument, Maturity Date	Jan. 26, 2028
2.50% notes due 2024 | Subsidiaries
Debt Instrument [Line Items]
Stated interest rate	2.50%	2.50%
Debt Instrument, Maturity Date	Jul. 23, 2024	Jul. 23, 2024
Minimum | Floating-rate based on FHLB auction rate due 2026 | Subsidiaries
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Mar. 4, 2026
Maximum | Floating-rate based on FHLB auction rate due 2026 | Subsidiaries
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	May 20, 2026

Medium- And Long-Term Debt (Sch

Medium- And Long-Term Debt (Schedule Of Medium- And Long-Term Debt) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term Federal Home Loan Bank Advances		$ 3,800
Total medium- and long-term debt		7,434	$ 7,269
Parent Company
Debt Instrument [Line Items]
Medium-term notes		1,559	1,471
Total medium- and long-term debt		1,841	1,735
Subsidiaries
Debt Instrument [Line Items]
Subordinated notes		594	562
Medium-term notes		1,199	1,172
Long-term Federal Home Loan Bank Advances		3,800	3,800
Total medium- and long-term debt		5,593	5,534
3.80% subordinated notes due 2026 | Parent Company
Debt Instrument [Line Items]
Subordinated notes	[1]	$ 282	$ 264
Stated interest rate		3.80%	3.80%
Maturity date		Jul. 22, 2026	Jul. 22, 2026
3.70% Notes Due 2023 | Parent Company
Debt Instrument [Line Items]
Medium-term notes	[1]	$ 917	$ 884
Stated interest rate		3.70%	3.70%
Maturity date		Jul. 31, 2023	Jul. 31, 2023
4.00% Notes Due 2029 | Parent Company
Debt Instrument [Line Items]
Medium-term notes	[1]	$ 642	$ 587
Stated interest rate		4.00%	4.00%
Maturity date		Feb. 1, 2029	Feb. 1, 2029
4.00% subordinated notes due 2025 | Subsidiaries
Debt Instrument [Line Items]
Subordinated notes	[1]	$ 381	$ 360
Stated interest rate		4.00%	4.00%
Maturity date		Jul. 27, 2025	Jul. 27, 2025
7.875% subordinated notes due 2026 | Subsidiaries
Debt Instrument [Line Items]
Subordinated notes	[1]	$ 213	$ 202
Stated interest rate		7.875%	7.875%
Maturity date		Sep. 15, 2026	Sep. 15, 2026
2.50% notes due 2020 | Subsidiaries
Debt Instrument [Line Items]
Medium-term notes	[1],[2]	$ 675	$ 674
Stated interest rate		2.50%	2.50%
Maturity date		Jun. 2, 2020	Jun. 2, 2020
2.50% notes due 2024 | Subsidiaries
Debt Instrument [Line Items]
Medium-term notes	[1]	$ 524	$ 498
Stated interest rate		2.50%	2.50%
Maturity date		Jul. 23, 2024	Jul. 23, 2024
Floating-rate based on FHLB auction rate due 2026 | Subsidiaries
Debt Instrument [Line Items]
Long-term Federal Home Loan Bank Advances		$ 2,800	$ 2,800
Weighted-average interest rate		0.72%
Floating-rate based on FHLB auction rate due 2026 | Subsidiaries | Maximum
Debt Instrument [Line Items]
Maturity date		May 20, 2026
Floating-rate based on FHLB auction rate due 2026 | Subsidiaries | Minimum
Debt Instrument [Line Items]
Maturity date		Mar. 4, 2026
Floating-rate based on FHLB auction rate due 2028 | Subsidiaries
Debt Instrument [Line Items]
Long-term Federal Home Loan Bank Advances		$ 1,000	$ 1,000
Maturity date		Jan. 26, 2028
Weighted-average interest rate		1.47%
[1]	The fixed interest rates on these notes have been swapped to a variable rate and designated in a hedging relationship. Accordingly, carrying value has been adjusted to reflect the change in the fair value of the debt as a result of changes in the benchmark rate.
[2]	Due on June 2, 2020.

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) (Schedule Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Investment securities, Balance at beginning of period, net of tax		$ 65	$ (138)
Investment securities, Net unrealized holding gains arising during the period		323	109
Investment securities, Less: Provision for income taxes		76	25
Investment securities, Net unrealized holding gains arising during the period, net of tax		247	84
Investment securities, Net realized losses gains included in net securities losses		0	(8)
Investment securities, Less: Benefit for income taxes		0	(2)
Investment Securities, Reclassification adjustment for net securities losses included in net income, net of tax		0	(6)
Investment securities, Change in net unrealized gains on investment securities, net of tax		247	90
Investment securities, Balance at end of period, net of tax		312	(48)
Cash flow hedges, Balance at beginning of period, net of tax		34	0
Cash flow hedge: Net gains arising during the period		205	4
Cash flow hedges, Less: Provision for income tax		48	1
Change in net cash flow hedge gains arising during the period, net of tax		157	3
Net cash flow hedge losses included in interest and fees on loans		3	0
Cash flow hedges, Less: Provision for income tax		1	0
Cash flow hedges, reclassification adjustment for net cash flow hedge gains included in net income, net of tax		2	0
Cash flows hedges, Change in net gain on cash flow hedges		155	3
Cash flow hedges, Balance at end of period, net of tax	[1]	189	3
Benefit plans, Balance at beginning of period, net of tax		(334)	(471)
Benefit plans, Amortization of actuarial net loss		16	11
Benefit plans, Amortization of prior service credit		(7)	(7)
Benefit plans, Amounts recognized in other noninterest expenses		9	4
Benefit plans, Less: Provision for income taxes		2	1
Benefit plans, Change in defined benefit pension and other postretirement plans adjustment, net of tax		7	3
Benefit plans, Balance at end of period, net of tax		(327)	(468)
Total accumulated other comprehensive income (loss) at end of period, net of tax		$ 174	$ (513)	$ (235)
[1]	The Corporation expects to reclassify $66 million of net gains, net of tax, from accumulated other comprehensive income to earnings over the next twelve months if interest yield curves and notional amounts remain at March 31, 2020 levels.

Net (Loss) Income Per Common _3

Net (Loss) Income Per Common Share (Basic And Diluted Net Income Per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net (loss) income		$ (65)	$ 339
Income allocated to participating securities		0	2
Net (loss) income attributable to common shares		$ (65)	$ 337
Basic average shares		141	158
Basic net (loss) income per common share		$ (0.46)	$ 2.14
Basic average shares		141	158
Net effect of the assumed exercise of stock options		0	2
Diluted average shares		141	160
Diluted net (loss) income per common share		$ (0.46)	$ 2.11
Stock awards excluded because exercise prices were greater than average market price of shares		1.2	0.4
Stock awards excluded due to net loss	[1]	2.6	0
[1]	Average exercise price less than average market price of common shares for period; however, anti-dilutive due to net loss during the period.

Employee Benefit Plans Employee

Employee Benefit Plans Employee Benefit Plans (Net Periodic Defined Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Net periodic defined benefit (credit) cost	$ (5)	$ (7)
Qualified Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Total other components of net benefit (credit) cost	(16)	(18)
Net periodic defined benefit (credit) cost	(8)	(10)
Qualified Defined Benefit Pension Plan | Component recognized in salaries and benefits expense
Defined Benefit Plan Disclosure [Line Items]
Service cost	8	8
Qualified Defined Benefit Pension Plan | Component recognized in noninterest expenses
Defined Benefit Plan Disclosure [Line Items]
Interest Cost	18	20
Expected return on plan assets	(43)	(42)
Amortization of prior service credit	(5)	(5)
Amortization of net loss	14	9
Non-Qualified Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Total other components of net benefit (credit) cost	2	2
Net periodic defined benefit (credit) cost	3	3
Non-Qualified Defined Benefit Pension Plan | Component recognized in salaries and benefits expense
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1
Non-Qualified Defined Benefit Pension Plan | Component recognized in noninterest expenses
Defined Benefit Plan Disclosure [Line Items]
Interest Cost	2	2
Amortization of prior service credit	(2)	(2)
Amortization of net loss	2	2
Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Net periodic defined benefit (credit) cost	0	0
Postretirement Benefit Plan | Component recognized in noninterest expenses
Defined Benefit Plan Disclosure [Line Items]
Interest Cost	0	1
Expected return on plan assets	$ 0	$ (1)

Income Taxes And Tax-Related _2

Income Taxes And Tax-Related Items Income Taxes And Tax-Related Items (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Unrecognized tax benefits	$ 19	$ 17
Tax-related interest and penalties payable	6	8
Net deferred tax assets	(13)	(42)
State net operating loss carryforwards	3	3
Valuation allowance for deferred tax assets	$ 3	$ 3
Minimum
Years state net operating loss carryforwards expire	Dec. 31, 2020
Maximum
Years state net operating loss carryforwards expire	Dec. 31, 2029

Contingent Liabilities (Narrati

Contingent Liabilities (Narrative) (Details) - USD ($) $ in Millions	Jan. 17, 2014	Mar. 31, 2020	Mar. 31, 2019
Loss Contingencies [Line Items]
Legal fees		$ 2	$ 1
Pending Litigation | Minimum
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss		0
Pending Litigation | Maximum
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss		$ 45
Butte Local Development v. Masters Group v. Comerica Bank
Loss Contingencies [Line Items]
Amount of damages awarded by the jury	$ 52

Business Segment Information (N

Business Segment Information (Narrative) (Details)	3 Months Ended
	Mar. 31, 2020segmentsmarkets
Segment Reporting [Abstract]
Number of Major Business Segments | segments	3
Number of Primary Market Segments | markets	3

Business Segment Information (B

Business Segment Information (Business Segment Financial Results) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Net interest income (expense)		$ 513	$ 606
Provision for credit losses		411	(13)
Noninterest income		237	238
Noninterest expenses		425	433
(Benefit) provision for income taxes		(21)	85
Net (loss) income		(65)	339
Net credit-related charge-offs (recoveries)		84	11
Assets, average		73,265	69,771
Loans, average		49,604	49,677
Deposits, average		$ 56,768	$ 53,996
Return on average assets	[1]	(0.35%)	1.97%
Efficiency ratio	[2]	56.57%	50.81%
Business Bank
Net interest income (expense)		$ 380	$ 412
Provision for credit losses		396	(6)
Noninterest income		127	136
Noninterest expenses		194	198
(Benefit) provision for income taxes		(20)	82
Net (loss) income		(63)	274
Net credit-related charge-offs (recoveries)		83	12
Assets, average		44,254	43,909
Loans, average		42,593	42,538
Deposits, average		$ 30,230	$ 28,463
Return on average assets	[1]	(0.58%)	2.53%
Efficiency ratio	[2]	38.47%	36.24%
Retail Bank
Net interest income (expense)		$ 125	$ 146
Provision for credit losses		3	(4)
Noninterest income		28	31
Noninterest expenses		149	145
(Benefit) provision for income taxes		0	8
Net (loss) income		1	28
Net credit-related charge-offs (recoveries)		1	0
Assets, average		2,864	2,812
Loans, average		2,075	2,103
Deposits, average		$ 21,195	$ 20,470
Return on average assets	[1]	0.03%	0.54%
Efficiency ratio	[2]	96.03%	81.34%
Wealth Management
Net interest income (expense)		$ 41	$ 48
Provision for credit losses		12	(5)
Noninterest income		70	64
Noninterest expenses		72	72
(Benefit) provision for income taxes		6	11
Net (loss) income		21	34
Net credit-related charge-offs (recoveries)		0	(1)
Assets, average		5,078	5,174
Loans, average		4,936	5,036
Deposits, average		$ 4,025	$ 3,801
Return on average assets	[1]	1.69%	2.67%
Efficiency ratio	[2]	64.28%	64.42%
Finance
Net interest income (expense)		$ (44)	$ (15)
Provision for credit losses		0	0
Noninterest income		14	3
Noninterest expenses		0	0
(Benefit) provision for income taxes		(8)	(4)
Net (loss) income		(22)	(8)
Net credit-related charge-offs (recoveries)		0	0
Assets, average		14,285	13,585
Loans, average		0	0
Deposits, average		1,136	1,130
Other
Net interest income (expense)		11	15
Provision for credit losses		0	2
Noninterest income		(2)	4
Noninterest expenses		10	18
(Benefit) provision for income taxes	[3]	1	(12)
Net (loss) income		(2)	11
Net credit-related charge-offs (recoveries)		0	0
Assets, average		6,784	4,291
Loans, average		0	0
Deposits, average		$ 182	$ 132
[1]	Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.
[2]	Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net (losses) gains from securities and a derivative contract tied to the conversion rate of Visa Class B shares.
[3]	Included discrete tax benefits of $3 million and $11 million for the three months ended March 31, 2020 and 2019 , respectively.

Business Segment Information (M

Business Segment Information (Market Segment Financial Results) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Net interest income (expense)		$ 513	$ 606
Provision for credit losses		411	(13)
Noninterest income		237	238
Noninterest expenses		425	433
(Benefit) provision for income taxes		(21)	85
Net (loss) income		(65)	339
Net credit-related charge-offs (recoveries)		84	11
Assets, average		73,265	69,771
Loans, average		49,604	49,677
Deposits, average		$ 56,768	$ 53,996
Return on average assets	[1]	(0.35%)	1.97%
Efficiency ratio	[2]	56.57%	50.81%
Michigan
Net interest income (expense)		$ 163	$ 187
Provision for credit losses		24	5
Noninterest income		72	72
Noninterest expenses		140	139
(Benefit) provision for income taxes		15	26
Net (loss) income		56	89
Net credit-related charge-offs (recoveries)		3	4
Assets, average		12,899	13,075
Loans, average		12,191	12,557
Deposits, average		$ 20,748	$ 19,893
Return on average assets	[1]	1.05%	1.76%
Efficiency ratio	[2]	58.91%	53.66%
California
Net interest income (expense)		$ 182	$ 205
Provision for credit losses		51	(1)
Noninterest income		36	40
Noninterest expenses		98	100
(Benefit) provision for income taxes		17	37
Net (loss) income		52	109
Net credit-related charge-offs (recoveries)		11	(3)
Assets, average		18,377	18,934
Loans, average		18,027	18,652
Deposits, average		$ 17,466	$ 16,238
Return on average assets	[1]	1.12%	2.33%
Efficiency ratio	[2]	44.99%	40.91%
Texas
Net interest income (expense)		$ 115	$ 122
Provision for credit losses		290	(11)
Noninterest income		30	32
Noninterest expenses		84	84
(Benefit) provision for income taxes		(50)	19
Net (loss) income		(179)	62
Net credit-related charge-offs (recoveries)		70	13
Assets, average		11,154	10,911
Loans, average		10,566	10,262
Deposits, average		$ 9,204	$ 8,697
Return on average assets	[1]	(6.45%)	2.31%
Efficiency ratio	[2]	58.25%	54.62%
Other Markets
Net interest income (expense)		$ 86	$ 92
Provision for credit losses		46	(8)
Noninterest income		87	87
Noninterest expenses		93	92
(Benefit) provision for income taxes		4	19
Net (loss) income		30	76
Net credit-related charge-offs (recoveries)		0	(3)
Assets, average		9,766	8,975
Loans, average		8,820	8,206
Deposits, average		$ 8,032	$ 7,906
Return on average assets	[1]	1.24%	3.41%
Efficiency ratio	[2]	53.76%	51.28%
Finance & Other
Net interest income (expense)		$ (33)	$ 0
Provision for credit losses		0	2
Noninterest income		12	7
Noninterest expenses		10	18
(Benefit) provision for income taxes	[3]	(7)	(16)
Net (loss) income		(24)	3
Net credit-related charge-offs (recoveries)		0	0
Assets, average		21,069	17,876
Loans, average		0	0
Deposits, average		$ 1,318	$ 1,262
[1]	Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.
[2]	Noninterest expenses as a percentage of the sum of net interest income and noninterest income excluding net (losses) gains from securities and a derivative contract tied to the conversion rate of Visa Class B shares.
[3]	Included discrete tax benefits of $3 million and $11 million for the three months ended March 31, 2020 and 2019 , respectively.

Revenue from Contracts with C_3

Revenue from Contracts with Customers (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		$ 185	$ 184
Other sources of noninterest income		52	54
Total noninterest income		237	238
Business Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		89	92
Other sources of noninterest income		38	44
Total noninterest income		127	136
Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		28	29
Other sources of noninterest income		0	2
Total noninterest income		28	31
Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		68	63
Other sources of noninterest income		2	1
Total noninterest income		70	64
Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0
Other sources of noninterest income		12	7
Total noninterest income		12	7
Credit and Debit Card [Member]
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		59	63
Credit and Debit Card [Member] | Business Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		49	53
Credit and Debit Card [Member] | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		9	9
Credit and Debit Card [Member] | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		1	1
Credit and Debit Card [Member] | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0
Service charges on deposit accounts
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		49	51
Service charges on deposit accounts | Business Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		32	33
Service charges on deposit accounts | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		16	17
Service charges on deposit accounts | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		1	1
Service charges on deposit accounts | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0
Fiduciary income
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		54	49
Fiduciary income | Business Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0
Fiduciary income | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0
Fiduciary income | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		54	49
Fiduciary income | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0
Commercial loan servicing fees
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[1]	4	4
Commercial loan servicing fees | Business Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[1]	4	4
Commercial loan servicing fees | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[1]	0	0
Commercial loan servicing fees | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[1]	0	0
Commercial loan servicing fees | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[1]	0	0
Brokerage Commissions Revenue [Member]
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		7	7
Brokerage Commissions Revenue [Member] | Business Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0
Brokerage Commissions Revenue [Member] | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0
Brokerage Commissions Revenue [Member] | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		7	7
Brokerage Commissions Revenue [Member] | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0
Other noninterest income
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[2]	12	10
Other noninterest income | Business Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[2]	4	2
Other noninterest income | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[2]	3	3
Other noninterest income | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[2]	5	5
Other noninterest income | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[2]	$ 0	$ 0
[1]	Included in commercial lending fees on the Consolidated Statements of Comprehensive Income.
[2]	Excludes derivative, warrant and other miscellaneous income.